Remove unnecessary code in /widget.

- Remove numerous blocklist entries that no longer apply.
- Remove CanComputeVirtualKeyCodeFromScanCode(), because it's always true.
- Remove ShowXP{Folder,File}Picker(), since we have native pickers on supported Windows versions.
- Remove the config.trim_on_minimize preference, which is pointless on NT6+ and will just cause problems if used.

Tag #22.

17 files changed, 197 insertions, 1155 deletions

diff --git a/widget/windows/GfxInfo.cpp b/widget/windows/GfxInfo.cpp
index 0cbd323ded..bfea418510 100644
--- a/widget/windows/GfxInfo.cpp
+++ b/widget/windows/GfxInfo.cpp
@@ -241,9 +241,6 @@ ParseIDFromDeviceID(const nsAString &key, const char *prefix, int length)
 // based on http://msdn.microsoft.com/en-us/library/ms724834(VS.85).aspx
 enum {
   kWindowsUnknown = 0,
-  kWindowsXP = 0x50001,
-  kWindowsServer2003 = 0x50002,
-  kWindowsVista = 0x60000,
   kWindows7 = 0x60001,
   kWindows8 = 0x60002,
   kWindows8_1 = 0x60003,
@@ -826,12 +823,6 @@ static OperatingSystem
 WindowsVersionToOperatingSystem(int32_t aWindowsVersion)
 {
   switch(aWindowsVersion) {
-    case kWindowsXP:
-      return OperatingSystem::WindowsXP;
-    case kWindowsServer2003:
-      return OperatingSystem::WindowsServer2003;
-    case kWindowsVista:
-      return OperatingSystem::WindowsVista;
     case kWindows7:
       return OperatingSystem::Windows7;
     case kWindows8:
@@ -860,11 +851,6 @@ GfxInfo::GetGfxDriverInfo()
     /*
      * NVIDIA entries
      */
-    APPEND_TO_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP,
-      (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
-      GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
-      DRIVER_LESS_THAN_OR_EQUAL, V(6,14,11,8745), "FEATURE_FAILURE_NV_XP", "nVidia driver > 187.45" );
-
     /*
      * The last 5 digit of the NVIDIA driver version maps to the version that
      * NVIDIA uses. The minor version (15, 16, 17) corresponds roughtly to the
@@ -875,33 +861,17 @@ GfxInfo::GetGfxDriverInfo()
      * 187.45 (late October 2009) and earlier contain a bug which can cause us
      * to crash on shutdown.
      */
-    APPEND_TO_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista,
-      (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
-      GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
-      DRIVER_LESS_THAN_OR_EQUAL, V(8,15,11,8745),
-      "FEATURE_FAILURE_NV_VISTA_15", "nVidia driver > 187.45" );
     APPEND_TO_DRIVER_BLOCKLIST(OperatingSystem::Windows7,
       (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
       GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
       DRIVER_LESS_THAN_OR_EQUAL, V(8,15,11,8745),
       "FEATURE_FAILURE_NV_W7_15", "nVidia driver > 187.45" );
-    APPEND_TO_DRIVER_BLOCKLIST_RANGE(OperatingSystem::WindowsVista,
-      (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
-      GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
-      DRIVER_BETWEEN_INCLUSIVE_START, V(8,16,10,0000), V(8,16,11,8745),
-      "FEATURE_FAILURE_NV_VISTA_16", "nVidia driver > 187.45" );
     APPEND_TO_DRIVER_BLOCKLIST_RANGE(OperatingSystem::Windows7,
       (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
       GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
       DRIVER_BETWEEN_INCLUSIVE_START, V(8,16,10,0000), V(8,16,11,8745),
       "FEATURE_FAILURE_NV_W7_16", "nVidia driver > 187.45" );
     // Telemetry doesn't show any driver in this range so it might not even be required.
-    APPEND_TO_DRIVER_BLOCKLIST_RANGE(OperatingSystem::WindowsVista,
-      (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
-      GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
-      DRIVER_BETWEEN_INCLUSIVE_START, V(8,17,10,0000), V(8,17,11,8745),
-      "FEATURE_FAILURE_NV_VISTA_17", "nVidia driver > 187.45" );
-    // Telemetry doesn't show any driver in this range so it might not even be required.
     APPEND_TO_DRIVER_BLOCKLIST_RANGE(OperatingSystem::Windows7,
       (nsAString&) GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), GfxDriverInfo::allDevices,
       GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
@@ -999,13 +969,6 @@ GfxInfo::GetGfxDriverInfo()
         nsIGfxInfo::FEATURE_DIRECT2D, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,                                               \
         DRIVER_BUILD_ID_LESS_THAN, driverVer, ruleId )
 
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::WindowsVista, IntelGMA500,   1006, "FEATURE_FAILURE_594877_1");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::WindowsVista, IntelGMA900,   GfxDriverInfo::allDriverVersions, "FEATURE_FAILURE_594877_2");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::WindowsVista, IntelGMA950,   1504, "FEATURE_FAILURE_594877_3");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::WindowsVista, IntelGMA3150,  2124, "FEATURE_FAILURE_594877_4");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::WindowsVista, IntelGMAX3000, 1666, "FEATURE_FAILURE_594877_5");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::WindowsVista, IntelHDGraphicsToSandyBridge, 2202, "FEATURE_FAILURE_594877_6");
-
     IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::Windows7, IntelGMA500,   2026, "FEATURE_FAILURE_594877_7");
     IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::Windows7, IntelGMA900,   GfxDriverInfo::allDriverVersions, "FEATURE_FAILURE_594877_8");
     IMPLEMENT_INTEL_DRIVER_BLOCKLIST_D2D(OperatingSystem::Windows7, IntelGMA950,   1930, "FEATURE_FAILURE_594877_9");
@@ -1022,31 +985,6 @@ GfxInfo::GetGfxDriverInfo()
       nsIGfxInfo::FEATURE_DIRECT2D, nsIGfxInfo::FEATURE_BLOCKED_DEVICE,
       DRIVER_LESS_THAN, GfxDriverInfo::allDriverVersions, "FEATURE_FAILURE_1180379");
 
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelGMA500,   V(3,0,20,3200), "FEATURE_FAILURE_INTEL_1");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelGMA900,   V(6,14,10,4764), "FEATURE_FAILURE_INTEL_2");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelGMA950,   V(6,14,10,4926), "FEATURE_FAILURE_INTEL_3");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelGMA3150,  V(6,14,10,5134), "FEATURE_FAILURE_INTEL_4");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelGMAX3000, V(6,14,10,5218), "FEATURE_FAILURE_INTEL_5");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelGMAX4500HD, V(6,14,10,4969), "FEATURE_FAILURE_INTEL_6");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsXP, IntelHDGraphicsToSandyBridge, V(6,14,10,4969), "FEATURE_FAILURE_INTEL_7");
-
-    // StrechRect seems to suffer from precision issues which leads to artifacting
-    // during content drawing starting with at least version 6.14.10.5082
-    // and going until 6.14.10.5218. See bug 919454 and bug 949275 for more info.
-    APPEND_TO_DRIVER_BLOCKLIST_RANGE(OperatingSystem::WindowsXP,
-      const_cast<nsAString&>(GfxDriverInfo::GetDeviceVendor(VendorIntel)),
-      const_cast<GfxDeviceFamily*>(GfxDriverInfo::GetDeviceFamily(IntelGMAX4500HD)),
-      GfxDriverInfo::allFeatures, nsIGfxInfo::FEATURE_BLOCKED_DRIVER_VERSION,
-      DRIVER_BETWEEN_EXCLUSIVE, V(6,14,10,5076), V(6,14,10,5218), "FEATURE_FAILURE_INTEL_8", "6.14.10.5218");
-
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelGMA500,   V(3,0,20,3200), "FEATURE_FAILURE_INTEL_9");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelGMA900,   GfxDriverInfo::allDriverVersions, "FEATURE_FAILURE_INTEL_10");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelGMA950,   V(7,14,10,1504), "FEATURE_FAILURE_INTEL_11");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelGMA3150,  V(7,14,10,1910), "FEATURE_FAILURE_INTEL_12");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelGMAX3000, V(7,15,10,1666), "FEATURE_FAILURE_INTEL_13");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelGMAX4500HD, V(7,15,10,1666), "FEATURE_FAILURE_INTEL_14");
-    IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::WindowsVista, IntelHDGraphicsToSandyBridge, V(7,15,10,1666), "FEATURE_FAILURE_INTEL_15");
-
     IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::Windows7, IntelGMA500,   V(5,0,0,2026), "FEATURE_FAILURE_INTEL_16");
     IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::Windows7, IntelGMA900,   GfxDriverInfo::allDriverVersions, "FEATURE_FAILURE_INTEL_17");
     IMPLEMENT_INTEL_DRIVER_BLOCKLIST(OperatingSystem::Windows7, IntelGMA950,   V(8,15,10,1930), "FEATURE_FAILURE_INTEL_18");
@@ -1300,23 +1238,6 @@ GfxInfo::GetFeatureStatusImpl(int32_t aFeature,
       return NS_OK;
     }
 
-    // special-case the WinXP test slaves: they have out-of-date drivers, but we still want to
-    // whitelist them, actually we do know that this combination of device and driver version
-    // works well.
-    if (mWindowsVersion == kWindowsXP &&
-        adapterVendorID.Equals(GfxDriverInfo::GetDeviceVendor(VendorNVIDIA), nsCaseInsensitiveStringComparator()) &&
-        adapterDeviceID.LowerCaseEqualsLiteral("0x0861") && // GeForce 9400
-        driverVersion == V(6,14,11,7756))
-    {
-      *aStatus = FEATURE_STATUS_OK;
-      return NS_OK;
-    }
-
-    // Windows Server 2003 should be just like Windows XP for present purpose, but still has a different version number.
-    // OTOH Windows Server 2008 R1 and R2 already have the same version numbers as Vista and Seven respectively
-    if (os == OperatingSystem::WindowsServer2003)
-      os = OperatingSystem::WindowsXP;
-
     if (mHasDriverVersionMismatch) {
       *aStatus = nsIGfxInfo::FEATURE_BLOCKED_MISMATCHED_VERSION;
       return NS_OK;
diff --git a/widget/windows/KeyboardLayout.cpp b/widget/windows/KeyboardLayout.cpp
index 11f6578747..341a40c18d 100644
--- a/widget/windows/KeyboardLayout.cpp
+++ b/widget/windows/KeyboardLayout.cpp
@@ -1363,34 +1363,6 @@ NativeKey::InitWithKeyChar()
         break;
       }
 
-      if (!CanComputeVirtualKeyCodeFromScanCode()) {
-        // The right control key and the right alt key are extended keys.
-        // Therefore, we never get VK_RCONTRL and VK_RMENU for the result of
-        // MapVirtualKeyEx() on WinXP or WinServer2003.
-        //
-        // If VK_SHIFT, VK_CONTROL or VK_MENU key message is caused by well
-        // known scan code, we should decide it as Right key.  Otherwise,
-        // decide it as Left key.
-        switch (mOriginalVirtualKeyCode) {
-          case VK_CONTROL:
-            mVirtualKeyCode =
-              mIsExtended && mScanCode == 0x1D ? VK_RCONTROL : VK_LCONTROL;
-            break;
-          case VK_MENU:
-            mVirtualKeyCode =
-              mIsExtended && mScanCode == 0x38 ? VK_RMENU : VK_LMENU;
-            break;
-          case VK_SHIFT:
-            // Neither left shift nor right shift is an extended key,
-            // let's use VK_LSHIFT for unknown mapping.
-            mVirtualKeyCode = VK_LSHIFT;
-            break;
-          default:
-            MOZ_CRASH("Unsupported mOriginalVirtualKeyCode");
-        }
-        break;
-      }
-
       NS_ASSERTION(!mVirtualKeyCode,
                    "mVirtualKeyCode has been computed already");
 
@@ -1447,11 +1419,6 @@ NativeKey::InitWithKeyChar()
       //       scancode, we cannot compute virtual keycode.  I.e., with such
       //       applications, we cannot generate proper KeyboardEvent.code value.
 
-      // We cannot compute the virtual key code from WM_CHAR message on WinXP
-      // if it's caused by an extended key.
-      if (!CanComputeVirtualKeyCodeFromScanCode()) {
-        break;
-      }
       mVirtualKeyCode = mOriginalVirtualKeyCode =
         ComputeVirtualKeyCodeFromScanCodeEx();
       NS_ASSERTION(mVirtualKeyCode, "Failed to compute virtual keycode");
@@ -1869,18 +1836,6 @@ NativeKey::GetKeyLocation() const
   }
 }
 
-bool
-NativeKey::CanComputeVirtualKeyCodeFromScanCode() const
-{
-  // Vista or later supports ScanCodeEx.
-  if (IsVistaOrLater()) {
-    return true;
-  }
-  // Otherwise, MapVirtualKeyEx() can compute virtual keycode only with
-  // non-extended key.
-  return !mIsExtended;
-}
-
 uint8_t
 NativeKey::ComputeVirtualKeyCodeFromScanCode() const
 {
@@ -1894,12 +1849,6 @@ NativeKey::ComputeVirtualKeyCodeFromScanCodeEx() const
   // MapVirtualKeyEx() has been improved for supporting extended keys since
   // Vista.  When we call it for mapping a scancode of an extended key and
   // a virtual keycode, we need to add 0xE000 to the scancode.
-  // On the other hand, neither WinXP nor WinServer2003 doesn't support 0xE000.
-  // Therefore, we have no way to get virtual keycode from scan code of
-  // extended keys.
-  if (NS_WARN_IF(!CanComputeVirtualKeyCodeFromScanCode())) {
-    return 0;
-  }
   return static_cast<uint8_t>(
            ::MapVirtualKeyEx(GetScanCodeWithExtendedFlag(), MAPVK_VSC_TO_VK_EX,
                              mKeyboardLayout));
@@ -1910,8 +1859,7 @@ NativeKey::ComputeScanCodeExFromVirtualKeyCode(UINT aVirtualKeyCode) const
 {
   return static_cast<uint16_t>(
            ::MapVirtualKeyEx(aVirtualKeyCode,
-                             IsVistaOrLater() ? MAPVK_VK_TO_VSC_EX :
-                                                MAPVK_VK_TO_VSC,
+                             MAPVK_VK_TO_VSC_EX,
                              mKeyboardLayout));
 }
 
@@ -4345,8 +4293,7 @@ KeyboardLayout::LoadLayout(HKL aLayout)
 
   if (MOZ_LOG_TEST(sKeyboardLayoutLogger, LogLevel::Verbose)) {
     static const UINT kExtendedScanCode[] = { 0x0000, 0xE000 };
-    static const UINT kMapType =
-      IsVistaOrLater() ? MAPVK_VSC_TO_VK_EX : MAPVK_VSC_TO_VK;
+    static const UINT kMapType = MAPVK_VSC_TO_VK_EX;
     MOZ_LOG(sKeyboardLayoutLogger, LogLevel::Verbose,
       ("Logging virtual keycode values for scancode (0x%p)...",
        mKeyboardLayout));
@@ -4358,11 +4305,6 @@ KeyboardLayout::LoadLayout(HKL aLayout)
         MOZ_LOG(sKeyboardLayoutLogger, LogLevel::Verbose,
           ("0x%04X, %s", scanCode, kVirtualKeyName[virtualKeyCode]));
       }
-      // XP and Server 2003 don't support 0xE0 prefix of the scancode.
-      // Therefore, we don't need to continue on them.
-      if (!IsVistaOrLater()) {
-        break;
-      }
     }
   }
 }
diff --git a/widget/windows/KeyboardLayout.h b/widget/windows/KeyboardLayout.h
index dd2ac0bfce..70aacc80e6 100644
--- a/widget/windows/KeyboardLayout.h
+++ b/widget/windows/KeyboardLayout.h
@@ -560,11 +560,6 @@ private:
   bool GetFollowingCharMessage(MSG& aCharMsg);
 
   /**
-   * Whether the key event can compute virtual keycode from the scancode value.
-   */
-  bool CanComputeVirtualKeyCodeFromScanCode() const;
-
-  /**
    * Wraps MapVirtualKeyEx() with MAPVK_VSC_TO_VK.
    */
   uint8_t ComputeVirtualKeyCodeFromScanCode() const;
diff --git a/widget/windows/TSFTextStore.cpp b/widget/windows/TSFTextStore.cpp
index fb0505aa37..7224126b8d 100644
--- a/widget/windows/TSFTextStore.cpp
+++ b/widget/windows/TSFTextStore.cpp
@@ -5762,8 +5762,7 @@ TSFTextStore::Initialize()
     return;
   }
 
-  bool enableTsf =
-    IsVistaOrLater() && Preferences::GetBool(kPrefNameEnableTSF, false);
+  bool enableTsf = Preferences::GetBool(kPrefNameEnableTSF, false);
   MOZ_LOG(sTextStoreLog, LogLevel::Info,
     ("  TSFTextStore::Initialize(), TSF is %s",
      enableTsf ? "enabled" : "disabled"));
diff --git a/widget/windows/WinMouseScrollHandler.cpp b/widget/windows/WinMouseScrollHandler.cpp
index 10937ba519..e157b1be2d 100644
--- a/widget/windows/WinMouseScrollHandler.cpp
+++ b/widget/windows/WinMouseScrollHandler.cpp
@@ -992,10 +992,7 @@ MouseScrollHandler::SystemSettings::InitScrollChars()
                                      &mScrollChars, 0)) {
     MOZ_LOG(gMouseScrollLog, LogLevel::Info,
       ("MouseScroll::SystemSettings::InitScrollChars(): ::SystemParametersInfo("
-       "SPI_GETWHEELSCROLLCHARS) failed, %s",
-       IsVistaOrLater() ?
-         "this is unexpected on Vista or later" :
-         "but on XP or earlier, this is not a problem"));
+       "SPI_GETWHEELSCROLLCHARS) failed, this is unexpected on Vista or later"));
     // XXX Should we use DefaultScrollChars()?
     mScrollChars = 1;
   }
@@ -1081,7 +1078,7 @@ bool
 MouseScrollHandler::SystemSettings::IsOverridingSystemScrollSpeedAllowed()
 {
   return mScrollLines == DefaultScrollLines() &&
-         (!IsVistaOrLater() || mScrollChars == DefaultScrollChars());
+         mScrollChars == DefaultScrollChars();
 }
 
 /******************************************************************************
diff --git a/widget/windows/WinTaskbar.cpp b/widget/windows/WinTaskbar.cpp
index 698b7ec0e5..a2c553dea7 100644
--- a/widget/windows/WinTaskbar.cpp
+++ b/widget/windows/WinTaskbar.cpp
@@ -339,9 +339,6 @@ WinTaskbar::GetDefaultGroupId(nsAString & aDefaultGroupId) {
 // (static) Called from AppShell
 bool
 WinTaskbar::RegisterAppUserModelID() {
-  if (!IsWin7OrLater())
-    return false;
-
   SetCurrentProcessExplicitAppUserModelIDPtr funcAppUserModelID = nullptr;
   bool retVal = false;
 
@@ -372,7 +369,7 @@ NS_IMETHODIMP
 WinTaskbar::GetAvailable(bool *aAvailable) {
   // ITaskbarList4::HrInit() may fail with shell extensions like blackbox
   // installed. Initialize early to return available=false in those cases.
-  *aAvailable = IsWin7OrLater() && Initialize();
+  *aAvailable = Initialize();
 
   return NS_OK;
 }
diff --git a/widget/windows/WinUtils.cpp b/widget/windows/WinUtils.cpp
index 149513b2fa..418a77182b 100644
--- a/widget/windows/WinUtils.cpp
+++ b/widget/windows/WinUtils.cpp
@@ -462,7 +462,7 @@ static NtTestAlertPtr sNtTestAlert = nullptr;
 void
 WinUtils::Initialize()
 {
-  if (!sDwmDll && IsVistaOrLater()) {
+  if (!sDwmDll) {
     sDwmDll = ::LoadLibraryW(kDwmLibraryName);
 
     if (sDwmDll) {
@@ -628,16 +628,14 @@ GETPROCESSDPIAWARENESSPROC sGetProcessDpiAwareness;
 static bool
 SlowIsPerMonitorDPIAware()
 {
-  if (IsVistaOrLater()) {
-    // Intentionally leak the handle.
-    HMODULE shcore =
-      LoadLibraryEx(L"shcore", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
-    if (shcore) {
-      sGetDpiForMonitor =
-        (GETDPIFORMONITORPROC) GetProcAddress(shcore, "GetDpiForMonitor");
-      sGetProcessDpiAwareness =
-        (GETPROCESSDPIAWARENESSPROC) GetProcAddress(shcore, "GetProcessDpiAwareness");
-    }
+  // Intentionally leak the handle.
+  HMODULE shcore =
+    LoadLibraryEx(L"shcore", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
+  if (shcore) {
+    sGetDpiForMonitor =
+      (GETDPIFORMONITORPROC) GetProcAddress(shcore, "GetDpiForMonitor");
+    sGetProcessDpiAwareness =
+      (GETPROCESSDPIAWARENESSPROC) GetProcAddress(shcore, "GetProcessDpiAwareness");
   }
   PROCESS_DPI_AWARENESS dpiAwareness;
   return sGetDpiForMonitor && sGetProcessDpiAwareness &&
@@ -760,7 +758,7 @@ static DWORD
 GetWaitFlags()
 {
   DWORD result = MWMO_INPUTAVAILABLE;
-  if (IsVistaOrLater() && XRE_IsContentProcess()) {
+  if (XRE_IsContentProcess()) {
     result |= MWMO_ALERTABLE;
   }
   return result;
@@ -1878,7 +1876,7 @@ WinUtils::IsTouchDeviceSupportPresent()
 uint32_t
 WinUtils::GetMaxTouchPoints()
 {
-  if (IsWin7OrLater() && IsTouchDeviceSupportPresent()) {
+  if (IsTouchDeviceSupportPresent()) {
     return GetSystemMetrics(SM_MAXIMUMTOUCHES);
   }
   return 0;
@@ -1893,11 +1891,6 @@ typedef DWORD (WINAPI * GetFinalPathNameByHandlePtr)(HANDLE hFile,
 bool
 WinUtils::ResolveJunctionPointsAndSymLinks(std::wstring& aPath)
 {
-  // Users folder was introduced with Vista.
-  if (!IsVistaOrLater()) {
-    return true;
-  }
-
   wchar_t path[MAX_PATH] = { 0 };
 
   nsAutoHandle handle(
@@ -2025,21 +2018,19 @@ WinUtils::GetAppInitDLLs(nsAString& aOutput)
   }
   nsAutoRegKey key(hkey);
   LONG status;
-  if (IsVistaOrLater()) {
-    const wchar_t kLoadAppInitDLLs[] = L"LoadAppInit_DLLs";
-    DWORD loadAppInitDLLs = 0;
-    DWORD loadAppInitDLLsLen = sizeof(loadAppInitDLLs);
-    status = RegQueryValueExW(hkey, kLoadAppInitDLLs, nullptr,
-                              nullptr, (LPBYTE)&loadAppInitDLLs,
-                              &loadAppInitDLLsLen);
-    if (status != ERROR_SUCCESS) {
-      return false;
-    }
-    if (!loadAppInitDLLs) {
-      // If loadAppInitDLLs is zero then AppInit_DLLs is disabled.
-      // In this case we'll return true along with an empty output string.
-      return true;
-    }
+  const wchar_t kLoadAppInitDLLs[] = L"LoadAppInit_DLLs";
+  DWORD loadAppInitDLLs = 0;
+  DWORD loadAppInitDLLsLen = sizeof(loadAppInitDLLs);
+  status = RegQueryValueExW(hkey, kLoadAppInitDLLs, nullptr,
+                            nullptr, (LPBYTE)&loadAppInitDLLs,
+                            &loadAppInitDLLsLen);
+  if (status != ERROR_SUCCESS) {
+    return false;
+  }
+  if (!loadAppInitDLLs) {
+    // If loadAppInitDLLs is zero then AppInit_DLLs is disabled.
+    // In this case we'll return true along with an empty output string.
+    return true;
   }
   DWORD numBytes = 0;
   const wchar_t kAppInitDLLs[] = L"AppInit_DLLs";
diff --git a/widget/windows/nsDataObj.cpp b/widget/windows/nsDataObj.cpp
index fc45968ae3..02ec3b2fea 100644
--- a/widget/windows/nsDataObj.cpp
+++ b/widget/windows/nsDataObj.cpp
@@ -1148,8 +1148,7 @@ nsDataObj :: GetFileContentsInternetShortcut ( FORMATETC& aFE, STGMEDIUM& aSTG )
   const char *shortcutFormatStr;
   int totalLen;
   nsCString path;
-  if (!Preferences::GetBool(kShellIconPref, true) ||
-      !IsVistaOrLater()) {
+  if (!Preferences::GetBool(kShellIconPref, true)) {
     shortcutFormatStr = "[InternetShortcut]\r\nURL=%s\r\n";
     const int formatLen = strlen(shortcutFormatStr) - 2;  // don't include %s
     totalLen = formatLen + asciiUrl.Length();  // don't include null character
diff --git a/widget/windows/nsFilePicker.cpp b/widget/windows/nsFilePicker.cpp
index 53857cf5e4..4e942968ac 100644
--- a/widget/windows/nsFilePicker.cpp
+++ b/widget/windows/nsFilePicker.cpp
@@ -28,7 +28,6 @@
 #include "nsPIDOMWindow.h"
 #include "GeckoProfiler.h"
 
-using mozilla::IsVistaOrLater;
 using mozilla::IsWin8OrLater;
 using mozilla::MakeUnique;
 using mozilla::mscom::EnsureMTA;
@@ -219,191 +218,6 @@ STDMETHODIMP nsFilePicker::QueryInterface(REFIID refiid, void** ppvResult)
   return E_NOINTERFACE;
 }
 
-/*
- * XP picker callbacks
- */
-
-// Show - Display the file dialog
-int CALLBACK
-BrowseCallbackProc(HWND hwnd, UINT uMsg, LPARAM lParam, LPARAM lpData)
-{
-  if (uMsg == BFFM_INITIALIZED)
-  {
-    char16_t * filePath = (char16_t *) lpData;
-    if (filePath)
-      ::SendMessageW(hwnd, BFFM_SETSELECTIONW,
-                     TRUE /* true because lpData is a path string */,
-                     lpData);
-  }
-  return 0;
-}
-
-static void
-EnsureWindowVisible(HWND hwnd) 
-{
-  // Obtain the monitor which has the largest area of intersection 
-  // with the window, or nullptr if there is no intersection.
-  HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONULL);
-  if (!monitor) {
-    // The window is not visible, we should reposition it to the same place as its parent
-    HWND parentHwnd = GetParent(hwnd);
-    RECT parentRect;
-    GetWindowRect(parentHwnd, &parentRect);
-    SetWindowPos(hwnd, nullptr, parentRect.left, parentRect.top, 0, 0,
-                 SWP_NOACTIVATE | SWP_NOSIZE | SWP_NOZORDER);
-  }
-}
-
-// Callback hook which will ensure that the window is visible. Currently
-// only in use on os <= XP.
-UINT_PTR CALLBACK
-nsFilePicker::FilePickerHook(HWND hwnd,
-                             UINT msg,
-                             WPARAM wParam,
-                             LPARAM lParam) 
-{
-  switch(msg) {
-    case WM_NOTIFY:
-      {
-        LPOFNOTIFYW lpofn = (LPOFNOTIFYW) lParam;
-        if (!lpofn || !lpofn->lpOFN) {
-          return 0;
-        }
-        
-        if (CDN_INITDONE == lpofn->hdr.code) {
-          // The Window will be automatically moved to the last position after
-          // CDN_INITDONE.  We post a message to ensure the window will be visible
-          // so it will be done after the automatic last position window move.
-          PostMessage(hwnd, MOZ_WM_ENSUREVISIBLE, 0, 0);
-        }
-      }
-      break;
-    case MOZ_WM_ENSUREVISIBLE:
-      EnsureWindowVisible(GetParent(hwnd));
-      break;
-    case WM_INITDIALOG:
-      {
-        OPENFILENAMEW* pofn = reinterpret_cast<OPENFILENAMEW*>(lParam);
-        SetProp(hwnd, kDialogPtrProp, (HANDLE)pofn->lCustData);
-        nsFilePicker* picker = reinterpret_cast<nsFilePicker*>(pofn->lCustData);
-        if (picker) {
-          picker->SetDialogHandle(hwnd);
-          SetTimer(hwnd, kDialogTimerID, kDialogTimerTimeout, nullptr);
-        }
-      }
-      break;
-    case WM_TIMER:
-      {
-        // Check to see if our parent has been torn down, if so, we close too.
-        if (wParam == kDialogTimerID) {
-          nsFilePicker* picker = 
-            reinterpret_cast<nsFilePicker*>(GetProp(hwnd, kDialogPtrProp));
-          if (picker && picker->ClosePickerIfNeeded(true)) {
-            KillTimer(hwnd, kDialogTimerID);
-          }
-        }
-      }
-      break;
-  }
-  return 0;
-}
-
-
-// Callback hook which will dynamically allocate a buffer large enough
-// for the file picker dialog.  Currently only in use on  os <= XP.
-UINT_PTR CALLBACK
-nsFilePicker::MultiFilePickerHook(HWND hwnd,
-                                  UINT msg,
-                                  WPARAM wParam,
-                                  LPARAM lParam)
-{
-  switch (msg) {
-    case WM_INITDIALOG:
-      {
-        // Finds the child drop down of a File Picker dialog and sets the 
-        // maximum amount of text it can hold when typed in manually.
-        // A wParam of 0 mean 0x7FFFFFFE characters.
-        HWND comboBox = FindWindowEx(GetParent(hwnd), nullptr, 
-                                     L"ComboBoxEx32", nullptr );
-        if(comboBox)
-          SendMessage(comboBox, CB_LIMITTEXT, 0, 0);
-        // Store our nsFilePicker ptr for future use
-        OPENFILENAMEW* pofn = reinterpret_cast<OPENFILENAMEW*>(lParam);
-        SetProp(hwnd, kDialogPtrProp, (HANDLE)pofn->lCustData);
-        nsFilePicker* picker =
-          reinterpret_cast<nsFilePicker*>(pofn->lCustData);
-        if (picker) {
-          picker->SetDialogHandle(hwnd);
-          SetTimer(hwnd, kDialogTimerID, kDialogTimerTimeout, nullptr);
-        }
-      }
-      break;
-    case WM_NOTIFY:
-      {
-        LPOFNOTIFYW lpofn = (LPOFNOTIFYW) lParam;
-        if (!lpofn || !lpofn->lpOFN) {
-          return 0;
-        }
-        // CDN_SELCHANGE is sent when the selection in the list box of the file
-        // selection dialog changes
-        if (lpofn->hdr.code == CDN_SELCHANGE) {
-          HWND parentHWND = GetParent(hwnd);
-
-          // Get the required size for the selected files buffer
-          UINT newBufLength = 0; 
-          int requiredBufLength = CommDlg_OpenSave_GetSpecW(parentHWND, 
-                                                            nullptr, 0);
-          if(requiredBufLength >= 0)
-            newBufLength += requiredBufLength;
-          else
-            newBufLength += MAX_PATH;
-
-          // If the user selects multiple files, the buffer contains the 
-          // current directory followed by the file names of the selected 
-          // files. So make room for the directory path.  If the user
-          // selects a single file, it is no harm to add extra space.
-          requiredBufLength = CommDlg_OpenSave_GetFolderPathW(parentHWND, 
-                                                              nullptr, 0);
-          if(requiredBufLength >= 0)
-            newBufLength += requiredBufLength;
-          else
-            newBufLength += MAX_PATH;
-
-          // Check if lpstrFile and nMaxFile are large enough
-          if (newBufLength > lpofn->lpOFN->nMaxFile) {
-            if (lpofn->lpOFN->lpstrFile)
-              delete[] lpofn->lpOFN->lpstrFile;
-
-            // We allocate FILE_BUFFER_SIZE more bytes than is needed so that
-            // if the user selects a file and holds down shift and down to 
-            // select  additional items, we will not continuously reallocate
-            newBufLength += FILE_BUFFER_SIZE;
-
-            wchar_t* filesBuffer = new wchar_t[newBufLength];
-            ZeroMemory(filesBuffer, newBufLength * sizeof(wchar_t));
-
-            lpofn->lpOFN->lpstrFile = filesBuffer;
-            lpofn->lpOFN->nMaxFile  = newBufLength;
-          }
-        }
-      }
-      break;
-    case WM_TIMER:
-      {
-        // Check to see if our parent has been torn down, if so, we close too.
-        if (wParam == kDialogTimerID) {
-          nsFilePicker* picker =
-            reinterpret_cast<nsFilePicker*>(GetProp(hwnd, kDialogPtrProp));
-          if (picker && picker->ClosePickerIfNeeded(true)) {
-            KillTimer(hwnd, kDialogTimerID);
-          }
-        }
-      }
-      break;
-  }
-
-  return FilePickerHook(hwnd, msg, wParam, lParam);
-}
 
 /*
  * Vista+ callbacks
@@ -476,25 +290,18 @@ nsFilePicker::OnOverwrite(IFileDialog *pfd,
  */
 
 bool
-nsFilePicker::ClosePickerIfNeeded(bool aIsXPDialog)
+nsFilePicker::ClosePickerIfNeeded()
 {
   if (!mParentWidget || !mDlgWnd)
     return false;
 
   nsWindow *win = static_cast<nsWindow *>(mParentWidget.get());
-  // Note, the xp callbacks hand us an inner window, so we have to step up
-  // one to get the actual dialog.
-  HWND dlgWnd;
-  if (aIsXPDialog)
-    dlgWnd = GetParent(mDlgWnd);
-  else
-    dlgWnd = mDlgWnd;
-  if (IsWindow(dlgWnd) && IsWindowVisible(dlgWnd) && win->DestroyCalled()) {
+  if (IsWindow(mDlgWnd) && IsWindowVisible(mDlgWnd) && win->DestroyCalled()) {
     wchar_t className[64];
     // Make sure we have the right window
-    if (GetClassNameW(dlgWnd, className, mozilla::ArrayLength(className)) &&
+    if (GetClassNameW(mDlgWnd, className, mozilla::ArrayLength(className)) &&
         !wcscmp(className, L"#32770") &&
-        DestroyWindow(dlgWnd)) {
+        DestroyWindow(mDlgWnd)) {
       mDlgWnd = nullptr;
       return true;
     }
@@ -506,7 +313,7 @@ void
 nsFilePicker::PickerCallbackTimerFunc(nsITimer *aTimer, void *aCtx)
 {
   nsFilePicker* picker = (nsFilePicker*)aCtx;
-  if (picker->ClosePickerIfNeeded(false)) {
+  if (picker->ClosePickerIfNeeded()) {
     aTimer->Cancel();
   }
 }
@@ -523,62 +330,15 @@ nsFilePicker::SetDialogHandle(HWND aWnd)
  * Folder picker invocation
  */
 
-// Open the older XP style folder picker dialog. We end up in this call
-// on XP systems or when platform is built without the longhorn SDK.
-bool
-nsFilePicker::ShowXPFolderPicker(const nsString& aInitialDir)
-{
-  bool result = false;
-
-  auto dirBuffer = MakeUnique<wchar_t[]>(FILE_BUFFER_SIZE);
-  wcsncpy(dirBuffer.get(), aInitialDir.get(), FILE_BUFFER_SIZE);
-  dirBuffer[FILE_BUFFER_SIZE-1] = '\0';
-
-  AutoDestroyTmpWindow adtw((HWND)(mParentWidget.get() ?
-    mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW) : nullptr));
-
-  BROWSEINFOW browserInfo = {0};
-  browserInfo.pidlRoot       = nullptr;
-  browserInfo.pszDisplayName = dirBuffer.get();
-  browserInfo.lpszTitle      = mTitle.get();
-  browserInfo.ulFlags        = BIF_USENEWUI | BIF_RETURNONLYFSDIRS;
-  browserInfo.hwndOwner      = adtw.get(); 
-  browserInfo.iImage         = 0;
-  browserInfo.lParam         = reinterpret_cast<LPARAM>(this);
-
-  if (!aInitialDir.IsEmpty()) {
-    // the dialog is modal so that |initialDir.get()| will be valid in 
-    // BrowserCallbackProc. Thus, we don't need to clone it.
-    browserInfo.lParam = (LPARAM) aInitialDir.get();
-    browserInfo.lpfn   = &BrowseCallbackProc;
-  } else {
-    browserInfo.lParam = 0;
-    browserInfo.lpfn   = nullptr;
-  }
-
-  LPITEMIDLIST list = ::SHBrowseForFolderW(&browserInfo);
-  if (list) {
-    result = ::SHGetPathFromIDListW(list, dirBuffer.get());
-    if (result)
-      mUnicodeFile.Assign(static_cast<const wchar_t*>(dirBuffer.get()));
-    // free PIDL
-    CoTaskMemFree(list);
-  }
-
-  return result;
-}
-
 /*
- * Show a folder picker post Windows XP
- * 
+ * Show a folder picker.
+ *
  * @param aInitialDir   The initial directory, the last used directory will be
  *                      used if left blank.
- * @param aWasInitError Out parameter will hold true if there was an error
- *                      before the folder picker is shown.
  * @return true if a file was selected successfully.
 */
 bool
-nsFilePicker::ShowFolderPicker(const nsString& aInitialDir, bool &aWasInitError)
+nsFilePicker::ShowFolderPicker(const nsString& aInitialDir)
 {
   if (!IsWin8OrLater()) {
     // Some Windows 7 users are experiencing a race condition when some dlls
@@ -593,10 +353,8 @@ nsFilePicker::ShowFolderPicker(const nsString& aInitialDir, bool &aWasInitError)
   if (FAILED(CoCreateInstance(CLSID_FileOpenDialog, nullptr, CLSCTX_INPROC,
                               IID_IFileOpenDialog,
                               getter_AddRefs(dialog)))) {
-    aWasInitError = true;
     return false;
   }
-  aWasInitError = false;
 
   // hook up event callbacks
   dialog->Advise(this, &mFDECookie);
@@ -658,233 +416,15 @@ nsFilePicker::ShowFolderPicker(const nsString& aInitialDir, bool &aWasInitError)
  * File open and save picker invocation
  */
 
-/* static */ bool
-nsFilePicker::GetFileNameWrapper(OPENFILENAMEW* ofn, PickerType aType)
-{
-  MOZ_SEH_TRY {
-    if (aType == PICKER_TYPE_OPEN)
-      return ::GetOpenFileNameW(ofn);
-    else if (aType == PICKER_TYPE_SAVE)
-      return ::GetSaveFileNameW(ofn);
-  } MOZ_SEH_EXCEPT(true) {
-    NS_ERROR("nsFilePicker GetFileName win32 call generated an exception! This is bad!");
-  }
-  return false;
-}
-
-bool
-nsFilePicker::FilePickerWrapper(OPENFILENAMEW* ofn, PickerType aType)
-{
-  if (!ofn)
-    return false;
-  AutoWidgetPickerState awps(mParentWidget);
-  return GetFileNameWrapper(ofn, aType);
-}
-
-bool
-nsFilePicker::ShowXPFilePicker(const nsString& aInitialDir)
-{
-  OPENFILENAMEW ofn = {0};
-  ofn.lStructSize = sizeof(ofn);
-  nsString filterBuffer = mFilterList;
-                                
-  auto fileBuffer = MakeUnique<wchar_t[]>(FILE_BUFFER_SIZE);
-  wcsncpy(fileBuffer.get(),  mDefaultFilePath.get(), FILE_BUFFER_SIZE);
-  fileBuffer[FILE_BUFFER_SIZE-1] = '\0'; // null terminate in case copy truncated
-
-  if (!aInitialDir.IsEmpty()) {
-    ofn.lpstrInitialDir = aInitialDir.get();
-  }
-
-  AutoDestroyTmpWindow adtw((HWND) (mParentWidget.get() ?
-    mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW) : nullptr));
-
-  ofn.lpstrTitle   = (LPCWSTR)mTitle.get();
-  ofn.lpstrFilter  = (LPCWSTR)filterBuffer.get();
-  ofn.nFilterIndex = mSelectedType;
-  ofn.lpstrFile    = fileBuffer.get();
-  ofn.nMaxFile     = FILE_BUFFER_SIZE;
-  ofn.hwndOwner    = adtw.get();
-  ofn.lCustData    = reinterpret_cast<LPARAM>(this);
-  ofn.Flags = OFN_SHAREAWARE | OFN_LONGNAMES | OFN_OVERWRITEPROMPT |
-              OFN_HIDEREADONLY | OFN_PATHMUSTEXIST | OFN_ENABLESIZING | 
-              OFN_EXPLORER;
-
-  // Windows Vista and up won't allow you to use the new looking dialogs with
-  // a hook procedure.  The hook procedure fixes a problem on XP dialogs for
-  // file picker visibility.  Vista and up automatically ensures the file 
-  // picker is always visible.
-  if (!IsVistaOrLater()) {
-    ofn.lpfnHook = FilePickerHook;
-    ofn.Flags |= OFN_ENABLEHOOK;
-  }
-
-  // Handle add to recent docs settings
-  if (IsPrivacyModeEnabled() || !mAddToRecentDocs) {
-    ofn.Flags |= OFN_DONTADDTORECENT;
-  }
-
-  NS_NAMED_LITERAL_STRING(htmExt, "html");
-
-  if (!mDefaultExtension.IsEmpty()) {
-    ofn.lpstrDefExt = mDefaultExtension.get();
-  } else if (IsDefaultPathHtml()) {
-    // Get file extension from suggested filename to detect if we are
-    // saving an html file.
-    // This is supposed to append ".htm" if user doesn't supply an
-    // extension but the behavior is sort of weird:
-    // - Often appends ".html" even if you have an extension
-    // - It obeys your extension if you put quotes around name
-    ofn.lpstrDefExt = htmExt.get();
-  }
-
-  // When possible, instead of using OFN_NOCHANGEDIR to ensure the current
-  // working directory will not change from this call, we will retrieve the
-  // current working directory before the call and restore it after the 
-  // call.  This flag causes problems on Windows XP for paths that are
-  // selected like  C:test.txt where the user is currently at C:\somepath
-  // In which case expected result should be C:\somepath\test.txt
-  AutoRestoreWorkingPath restoreWorkingPath;
-  // If we can't get the current working directory, the best case is to
-  // use the OFN_NOCHANGEDIR flag
-  if (!restoreWorkingPath.HasWorkingPath()) {
-    ofn.Flags |= OFN_NOCHANGEDIR;
-  }
-
-  bool result = false;
-
-  switch(mMode) {
-    case modeOpen:
-      // FILE MUST EXIST!
-      ofn.Flags |= OFN_FILEMUSTEXIST;
-      result = FilePickerWrapper(&ofn, PICKER_TYPE_OPEN);
-      break;
-
-    case modeOpenMultiple:
-      ofn.Flags |= OFN_FILEMUSTEXIST | OFN_ALLOWMULTISELECT;
-
-      // The hook set here ensures that the buffer returned will always be
-      // large enough to hold all selected files.  The hook may modify the
-      // value of ofn.lpstrFile and deallocate the old buffer that it pointed
-      // to (fileBuffer). The hook assumes that the passed in value is heap 
-      // allocated and that the returned value should be freed by the caller.
-      // If the hook changes the buffer, it will deallocate the old buffer.
-      // This fix would be nice to have in Vista and up, but it would force
-      // the file picker to use the old style dialogs because hooks are not
-      // allowed in the new file picker UI.  We need to eventually move to
-      // the new Common File Dialogs for Vista and up.
-      if (!IsVistaOrLater()) {
-        ofn.lpfnHook = MultiFilePickerHook;
-        fileBuffer.release();
-        result = FilePickerWrapper(&ofn, PICKER_TYPE_OPEN);
-        fileBuffer.reset(ofn.lpstrFile);
-      } else {
-        result = FilePickerWrapper(&ofn, PICKER_TYPE_OPEN);
-      }
-      break;
-
-    case modeSave:
-      {
-        ofn.Flags |= OFN_NOREADONLYRETURN;
-
-        // Don't follow shortcuts when saving a shortcut, this can be used
-        // to trick users (bug 271732)
-        if (IsDefaultPathLink())
-          ofn.Flags |= OFN_NODEREFERENCELINKS;
-
-        result = FilePickerWrapper(&ofn, PICKER_TYPE_SAVE);
-        if (!result) {
-          // Error, find out what kind.
-          if (GetLastError() == ERROR_INVALID_PARAMETER ||
-              CommDlgExtendedError() == FNERR_INVALIDFILENAME) {
-            // Probably the default file name is too long or contains illegal
-            // characters. Try again, without a starting file name.
-            ofn.lpstrFile[0] = L'\0';
-            result = FilePickerWrapper(&ofn, PICKER_TYPE_SAVE);
-          }
-        }
-      }
-      break;
-
-    default:
-      NS_NOTREACHED("unsupported file picker mode");
-      return false;
-  }
-
-  if (!result)
-    return false;
-
-  // Remember what filter type the user selected
-  mSelectedType = (int16_t)ofn.nFilterIndex;
-
-  // Single file selection, we're done
-  if (mMode != modeOpenMultiple) {
-    GetQualifiedPath(fileBuffer.get(), mUnicodeFile);
-    return true;
-  }
-
-  // Set user-selected location of file or directory.  From msdn's "Open and
-  // Save As Dialog Boxes" section:
-  // If you specify OFN_EXPLORER, the directory and file name strings are '\0'
-  // separated, with an extra '\0' character after the last file name. This
-  // format enables the Explorer-style dialog boxes to return long file names
-  // that include spaces. 
-  wchar_t *current = fileBuffer.get();
-  
-  nsAutoString dirName(current);
-  // Sometimes dirName contains a trailing slash and sometimes it doesn't:
-  if (current[dirName.Length() - 1] != '\\')
-    dirName.Append((char16_t)'\\');
-  
-  while (current && *current && *(current + wcslen(current) + 1)) {
-    current = current + wcslen(current) + 1;
-    
-    nsCOMPtr<nsIFile> file = do_CreateInstance("@mozilla.org/file/local;1");
-    NS_ENSURE_TRUE(file, false);
-
-    // Only prepend the directory if the path specified is a relative path
-    nsAutoString path;
-    if (PathIsRelativeW(current)) {
-      path = dirName + nsDependentString(current);
-    } else {
-      path = current;
-    }
-
-    nsAutoString canonicalizedPath;
-    GetQualifiedPath(path.get(), canonicalizedPath);
-    if (NS_FAILED(file->InitWithPath(canonicalizedPath)) ||
-        !mFiles.AppendObject(file))
-      return false;
-  }
-  
-  // Handle the case where the user selected just one file. From msdn: If you
-  // specify OFN_ALLOWMULTISELECT and the user selects only one file the
-  // lpstrFile string does not have a separator between the path and file name.
-  if (current && *current && (current == fileBuffer.get())) {
-    nsCOMPtr<nsIFile> file = do_CreateInstance("@mozilla.org/file/local;1");
-    NS_ENSURE_TRUE(file, false);
-    
-    nsAutoString canonicalizedPath;
-    GetQualifiedPath(current, canonicalizedPath);
-    if (NS_FAILED(file->InitWithPath(canonicalizedPath)) ||
-        !mFiles.AppendObject(file))
-      return false;
-  }
-
-  return true;
-}
-
 /*
- * Show a file picker post Windows XP
- * 
+ * Show a file picker.
+ *
  * @param aInitialDir   The initial directory, the last used directory will be
  *                      used if left blank.
- * @param aWasInitError Out parameter will hold true if there was an error
- *                      before the file picker is shown.
  * @return true if a file was selected successfully.
 */
 bool
-nsFilePicker::ShowFilePicker(const nsString& aInitialDir, bool &aWasInitError)
+nsFilePicker::ShowFilePicker(const nsString& aInitialDir)
 {
   PROFILER_LABEL_FUNC(js::ProfileEntry::Category::OTHER);
 
@@ -902,18 +442,15 @@ nsFilePicker::ShowFilePicker(const nsString& aInitialDir, bool &aWasInitError)
     if (FAILED(CoCreateInstance(CLSID_FileOpenDialog, nullptr, CLSCTX_INPROC,
                                 IID_IFileOpenDialog,
                                 getter_AddRefs(dialog)))) {
-      aWasInitError = true;
       return false;
     }
   } else {
     if (FAILED(CoCreateInstance(CLSID_FileSaveDialog, nullptr, CLSCTX_INPROC,
                                 IID_IFileSaveDialog,
                                 getter_AddRefs(dialog)))) {
-      aWasInitError = true;
       return false;
     }
   }
-  aWasInitError = false;
 
   // hook up event callbacks
   dialog->Advise(this, &mFDECookie);
@@ -1080,22 +617,11 @@ nsFilePicker::ShowW(int16_t *aReturnVal)
   // with our context set temporarily to system-dpi-aware
   WinUtils::AutoSystemDpiAware dpiAwareness;
 
-  // Launch the XP file/folder picker on XP and as a fallback on Vista+. 
-  // The CoCreateInstance call to CLSID_FileOpenDialog fails with "(0x80040111)
-  // ClassFactory cannot supply requested class" when the checkbox for
-  // Disable Visual Themes is on in the compatability tab within the shortcut
-  // properties.
-  bool result = false, wasInitError = true;
+  bool result = false;
   if (mMode == modeGetFolder) {
-    if (IsVistaOrLater())
-      result = ShowFolderPicker(initialDir, wasInitError);
-    if (!result && wasInitError)
-      result = ShowXPFolderPicker(initialDir);
+    result = ShowFolderPicker(initialDir);
   } else {
-    if (IsVistaOrLater())
-      result = ShowFilePicker(initialDir, wasInitError);
-    if (!result && wasInitError)
-      result = ShowXPFilePicker(initialDir);
+    result = ShowFilePicker(initialDir);
   }
 
   // exit, and return returnCancel in aReturnVal
@@ -1247,48 +773,10 @@ nsFilePicker::InitNative(nsIWidget *aParent,
   mTitle.Assign(aTitle);
 }
 
-void 
-nsFilePicker::GetQualifiedPath(const wchar_t *aInPath, nsString &aOutPath)
-{
-  // Prefer a qualified path over a non qualified path.
-  // Things like c:file.txt would be accepted in Win XP but would later
-  // fail to open from the download manager.
-  wchar_t qualifiedFileBuffer[MAX_PATH];
-  if (PathSearchAndQualifyW(aInPath, qualifiedFileBuffer, MAX_PATH)) {
-    aOutPath.Assign(qualifiedFileBuffer);
-  } else {
-    aOutPath.Assign(aInPath);
-  }
-}
-
-void
-nsFilePicker::AppendXPFilter(const nsAString& aTitle, const nsAString& aFilter)
-{
-  mFilterList.Append(aTitle);
-  mFilterList.Append(char16_t('\0'));
-
-  if (aFilter.EqualsLiteral("..apps"))
-    mFilterList.AppendLiteral("*.exe;*.com");
-  else
-  {
-    nsAutoString filter(aFilter);
-    filter.StripWhitespace();
-    if (filter.EqualsLiteral("*"))
-      filter.AppendLiteral(".*");
-    mFilterList.Append(filter);
-  }
-
-  mFilterList.Append(char16_t('\0'));
-}
-
 NS_IMETHODIMP
 nsFilePicker::AppendFilter(const nsAString& aTitle, const nsAString& aFilter)
 {
-  if (IsVistaOrLater()) {
-    mComFilterList.Append(aTitle, aFilter);
-  } else {
-    AppendXPFilter(aTitle, aFilter);
-  }
+  mComFilterList.Append(aTitle, aFilter);
   return NS_OK;
 }
 
diff --git a/widget/windows/nsFilePicker.h b/widget/windows/nsFilePicker.h
index 90d8c15bc1..3d692b3d4f 100644
--- a/widget/windows/nsFilePicker.h
+++ b/widget/windows/nsFilePicker.h
@@ -87,32 +87,19 @@ public:
   HRESULT STDMETHODCALLTYPE OnOverwrite(IFileDialog *pfd, IShellItem *psi, FDE_OVERWRITE_RESPONSE *pResponse);
 
 protected:
-  enum PickerType {
-    PICKER_TYPE_OPEN,
-    PICKER_TYPE_SAVE,
-  };
-
   /* method from nsBaseFilePicker */
   virtual void InitNative(nsIWidget *aParent,
                           const nsAString& aTitle);
-  static void GetQualifiedPath(const wchar_t *aInPath, nsString &aOutPath);
   void GetFilterListArray(nsString& aFilterList);
-  static bool GetFileNameWrapper(OPENFILENAMEW* ofn, PickerType aType);
-  bool FilePickerWrapper(OPENFILENAMEW* ofn, PickerType aType);
-  bool ShowXPFolderPicker(const nsString& aInitialDir);
-  bool ShowXPFilePicker(const nsString& aInitialDir);
-  bool ShowFolderPicker(const nsString& aInitialDir, bool &aWasInitError);
-  bool ShowFilePicker(const nsString& aInitialDir, bool &aWasInitError);
-  void AppendXPFilter(const nsAString& aTitle, const nsAString& aFilter);
+  bool ShowFolderPicker(const nsString& aInitialDir);
+  bool ShowFilePicker(const nsString& aInitialDir);
   void RememberLastUsedDirectory();
   bool IsPrivacyModeEnabled();
   bool IsDefaultPathLink();
   bool IsDefaultPathHtml();
   void SetDialogHandle(HWND aWnd);
-  bool ClosePickerIfNeeded(bool aIsXPDialog);
+  bool ClosePickerIfNeeded();
   static void PickerCallbackTimerFunc(nsITimer *aTimer, void *aPicker);
-  static UINT_PTR CALLBACK MultiFilePickerHook(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
-  static UINT_PTR CALLBACK FilePickerHook(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
 
   nsCOMPtr<nsILoadContext> mLoadContext;
   nsCOMPtr<nsIWidget>    mParentWidget;
diff --git a/widget/windows/nsLookAndFeel.cpp b/widget/windows/nsLookAndFeel.cpp
index e649802b18..06eee37716 100644
--- a/widget/windows/nsLookAndFeel.cpp
+++ b/widget/windows/nsLookAndFeel.cpp
@@ -32,12 +32,8 @@ nsLookAndFeel::GetOperatingSystemVersion()
     version = eOperatingSystemVersion_Windows10;
   } else if (IsWin8OrLater()) {
     version = eOperatingSystemVersion_Windows8;
-  } else if (IsWin7OrLater()) {
-    version = eOperatingSystemVersion_Windows7;
-  } else if (IsVistaOrLater()) {
-    version = eOperatingSystemVersion_WindowsVista;
   } else {
-    version = eOperatingSystemVersion_WindowsXP;
+    version = eOperatingSystemVersion_Windows7;
   }
 
   return version;
@@ -183,8 +179,7 @@ nsLookAndFeel::NativeGetColor(ColorID aID, nscolor &aColor)
       idx = COLOR_HIGHLIGHT;
       break;
     case eColorID__moz_menubarhovertext:
-      if (!IsVistaOrLater() || !IsAppThemed())
-      {
+      if (!IsAppThemed()) {
         idx = nsUXThemeData::sFlatMenus ?
                 COLOR_HIGHLIGHTTEXT :
                 COLOR_MENUTEXT;
@@ -192,8 +187,7 @@ nsLookAndFeel::NativeGetColor(ColorID aID, nscolor &aColor)
       }
       // Fall through
     case eColorID__moz_menuhovertext:
-      if (IsVistaOrLater() && IsAppThemed())
-      {
+      if (IsAppThemed()) {
         res = ::GetColorFromTheme(eUXMenu,
                                   MENU_POPUPITEM, MPI_HOT, TMT_TEXTCOLOR, aColor);
         if (NS_SUCCEEDED(res))
@@ -285,7 +279,7 @@ nsLookAndFeel::NativeGetColor(ColorID aID, nscolor &aColor)
       aColor = NS_RGB(0, 0, 0);
       return NS_OK;
     case eColorID__moz_win_mediatext:
-      if (IsVistaOrLater() && IsAppThemed()) {
+      if (IsAppThemed()) {
         res = ::GetColorFromTheme(eUXMediaToolbar,
                                   TP_BUTTON, TS_NORMAL, TMT_TEXTCOLOR, aColor);
         if (NS_SUCCEEDED(res))
@@ -295,8 +289,7 @@ nsLookAndFeel::NativeGetColor(ColorID aID, nscolor &aColor)
       idx = COLOR_WINDOWTEXT;
       break;
     case eColorID__moz_win_communicationstext:
-      if (IsVistaOrLater() && IsAppThemed())
-      {
+      if (IsAppThemed()) {
         res = ::GetColorFromTheme(eUXCommunicationsToolbar,
                                   TP_BUTTON, TS_NORMAL, TMT_TEXTCOLOR, aColor);
         if (NS_SUCCEEDED(res))
diff --git a/widget/windows/nsNativeThemeWin.cpp b/widget/windows/nsNativeThemeWin.cpp
index 4ff6b0af96..8950dcf90f 100644
--- a/widget/windows/nsNativeThemeWin.cpp
+++ b/widget/windows/nsNativeThemeWin.cpp
@@ -39,7 +39,6 @@
 #include "nsUXThemeConstants.h"
 #include <algorithm>
 
-using mozilla::IsVistaOrLater;
 using namespace mozilla;
 using namespace mozilla::widget;
 
@@ -301,10 +300,6 @@ DrawThemeBGRTLAware(HANDLE aTheme, HDC aHdc, int aPart, int aState,
  *  aero basic max          0        2        1        2
  *  aero basic close        1        2        1        2
  *
- *  xp theme min            0        2        0        2
- *  xp theme max            0        2        1        2
- *  xp theme close          1        2        2        2
- *
  *  'cold' button padding - generic button padding, should
  *  be handled in css.
  *                       left      top    right   bottom
@@ -315,16 +310,11 @@ DrawThemeBGRTLAware(HANDLE aTheme, HDC aHdc, int aPart, int aState,
  *  aero basic min          0        0        1        0
  *  aero basic max          1        0        0        0
  *  aero basic close        0        0        0        0
- *
- *  xp theme min            0        0        1        0
- *  xp theme max            1        0        0        0
- *  xp theme close          0        0        0        0
  */
 
 enum CaptionDesktopTheme {
   CAPTION_CLASSIC = 0,
   CAPTION_BASIC,
-  CAPTION_XPTHEME,
 };
 
 enum CaptionButton {
@@ -358,8 +348,6 @@ AddPaddingRect(LayoutDeviceIntSize* aSize, CaptionButton button) {
   RECT offset;
   if (!IsAppThemed())
     offset = buttonData[CAPTION_CLASSIC].hotPadding[button];
-  else if (!IsVistaOrLater())
-    offset = buttonData[CAPTION_XPTHEME].hotPadding[button];
   else
     offset = buttonData[CAPTION_BASIC].hotPadding[button];
   aSize->width += offset.left + offset.right;
@@ -373,8 +361,6 @@ OffsetBackgroundRect(RECT& rect, CaptionButton button) {
   RECT offset;
   if (!IsAppThemed())
     offset = buttonData[CAPTION_CLASSIC].hotPadding[button];
-  else if (!IsVistaOrLater())
-    offset = buttonData[CAPTION_XPTHEME].hotPadding[button];
   else
     offset = buttonData[CAPTION_BASIC].hotPadding[button];
   rect.left += offset.left;
@@ -419,9 +405,7 @@ OffsetBackgroundRect(RECT& rect, CaptionButton button) {
 static const double kProgressDeterminateTimeSpan = 3.0;
 static const double kProgressIndeterminateTimeSpan = 5.0;
 // The width of the overlay used to animate the horizontal progress bar (Vista and later).
-static const int32_t kProgressHorizontalVistaOverlaySize = 120;
-// The width of the overlay used for the horizontal indeterminate progress bars on XP.
-static const int32_t kProgressHorizontalXPOverlaySize = 55;
+static const int32_t kProgressHorizontalOverlaySize = 120;
 // The height of the overlay used to animate the vertical progress bar (Vista and later).
 static const int32_t kProgressVerticalOverlaySize = 45;
 // The height of the overlay used for the vertical indeterminate progress bar (Vista and later).
@@ -435,18 +419,8 @@ static const int32_t kProgressClassicOverlaySize = 40;
  */
 static int32_t
 GetProgressOverlayStyle(bool aIsVertical)
-{ 
-  if (aIsVertical) {
-    if (IsVistaOrLater()) {
-      return PP_MOVEOVERLAYVERT;
-    }
-    return PP_CHUNKVERT;
-  } else {
-    if (IsVistaOrLater()) {
-      return PP_MOVEOVERLAY;
-    }
-    return PP_CHUNK;
-  }
+{
+  return aIsVertical ? PP_MOVEOVERLAYVERT : PP_MOVEOVERLAY;
 }
 
 /*
@@ -457,14 +431,11 @@ GetProgressOverlayStyle(bool aIsVertical)
 static int32_t
 GetProgressOverlaySize(bool aIsVertical, bool aIsIndeterminate)
 {
-  if (IsVistaOrLater()) {
-    if (aIsVertical) {
-      return aIsIndeterminate ? kProgressVerticalIndeterminateOverlaySize
-                              : kProgressVerticalOverlaySize;
-    }
-    return kProgressHorizontalVistaOverlaySize;
+  if (aIsVertical) {
+    return aIsIndeterminate ? kProgressVerticalIndeterminateOverlaySize
+                            : kProgressVerticalOverlaySize;
   }
-  return kProgressHorizontalXPOverlaySize;
+  return kProgressHorizontalOverlaySize;
 }
 
 /*
@@ -554,87 +525,6 @@ nsNativeThemeWin::CalculateProgressOverlayRect(nsIFrame* aFrame,
 }
 
 /*
- * DrawChunkProgressMeter - renders an xp style chunked progress meter. Called
- * by DrawProgressMeter.
- *
- * @param aTheme       progress theme handle
- * @param aHdc         hdc returned by gfxWindowsNativeDrawing
- * @param aPart        the PP_X progress part
- * @param aState       the theme state
- * @param aFrame       the elements frame
- * @param aWidgetRect  bounding rect for the widget
- * @param aClipRect    dirty rect that needs drawing.
- * @param aAppUnits    app units per device pixel
- * @param aIsIndeterm  is an indeterminate progress?
- * @param aIsVertical  render a vertical progress?
- * @param aIsRtl       direction is rtl
- */
-static void
-DrawChunkProgressMeter(HTHEME aTheme, HDC aHdc, int aPart,
-                       int aState, nsIFrame* aFrame, RECT* aWidgetRect,
-                       RECT* aClipRect, gfxFloat aAppUnits, bool aIsIndeterm,
-                       bool aIsVertical, bool aIsRtl)
-{
-  NS_ASSERTION(aTheme, "Bad theme.");
-  NS_ASSERTION(aHdc, "Bad hdc.");
-  NS_ASSERTION(aWidgetRect, "Bad rect.");
-  NS_ASSERTION(aClipRect, "Bad clip rect.");
-  NS_ASSERTION(aFrame, "Bad frame.");
-
-  // For horizontal meters, the theme lib paints the right graphic but doesn't
-  // paint the chunks, so we do that manually. For vertical meters, the theme
-  // library draws everything correctly.
-  if (aIsVertical) {
-    DrawThemeBackground(aTheme, aHdc, aPart, aState, aWidgetRect, aClipRect);
-    return;
-  }
-
-  // query for the proper chunk metrics
-  int chunkSize, spaceSize;
-  if (FAILED(GetThemeMetric(aTheme, aHdc, aPart, aState,
-                            TMT_PROGRESSCHUNKSIZE, &chunkSize)) ||
-      FAILED(GetThemeMetric(aTheme, aHdc, aPart, aState,
-                            TMT_PROGRESSSPACESIZE, &spaceSize))) {
-    DrawThemeBackground(aTheme, aHdc, aPart, aState, aWidgetRect, aClipRect);
-    return;
-  }
-
-  // render chunks
-  if (!aIsRtl || aIsIndeterm) {
-    for (int chunk = aWidgetRect->left; chunk <= aWidgetRect->right;
-         chunk += (chunkSize+spaceSize)) {
-      if (!aIsIndeterm && ((chunk + chunkSize) > aWidgetRect->right)) {
-        // aWidgetRect->right represents the end of the meter. Partial blocks
-        // don't get rendered with one exception, so exit here if we don't have
-        // a full chunk to draw.
-        // The above is true *except* when the meter is at 100% fill, in which
-        // case Windows renders any remaining partial block. Query the parent
-        // frame to find out if we're at 100%.
-        if (!IsProgressMeterFilled(aFrame)) {
-          break;
-        }
-      }
-      RECT bounds =
-        { chunk, aWidgetRect->top, chunk + chunkSize, aWidgetRect->bottom };
-      DrawThemeBackground(aTheme, aHdc, aPart, aState, &bounds, aClipRect);
-    }
-  } else {
-    // rtl needs to grow in the opposite direction to look right.
-    for (int chunk = aWidgetRect->right; chunk >= aWidgetRect->left;
-         chunk -= (chunkSize+spaceSize)) {
-      if ((chunk - chunkSize) < aWidgetRect->left) {
-        if (!IsProgressMeterFilled(aFrame)) {
-          break;
-        }
-      }
-      RECT bounds =
-        { chunk - chunkSize, aWidgetRect->top, chunk, aWidgetRect->bottom };
-      DrawThemeBackground(aTheme, aHdc, aPart, aState, &bounds, aClipRect);
-    }
-  }
-}
-
-/*
  * DrawProgressMeter - render an appropriate progress meter based on progress
  * meter style, orientation, and os. Note, this does not render the underlying
  * progress track.
@@ -653,8 +543,7 @@ void
 nsNativeThemeWin::DrawThemedProgressMeter(nsIFrame* aFrame, int aWidgetType,
                                           HANDLE aTheme, HDC aHdc,
                                           int aPart, int aState,
-                                          RECT* aWidgetRect, RECT* aClipRect,
-                                          gfxFloat aAppUnits)
+                                          RECT* aWidgetRect, RECT* aClipRect)
 {
   if (!aFrame || !aTheme || !aHdc)
     return;
@@ -665,12 +554,6 @@ nsNativeThemeWin::DrawThemedProgressMeter(nsIFrame* aFrame, int aWidgetType,
   RECT adjWidgetRect, adjClipRect;
   adjWidgetRect = *aWidgetRect;
   adjClipRect = *aClipRect;
-  if (!IsVistaOrLater()) {
-    // Adjust clipping out by one pixel. XP progress meters are inset,
-    // Vista+ are not.
-    InflateRect(&adjWidgetRect, 1, 1);
-    InflateRect(&adjClipRect, 1, 1);
-  }
 
   nsIFrame* parentFrame = aFrame->GetParent();
   if (!parentFrame) {
@@ -685,20 +568,13 @@ nsNativeThemeWin::DrawThemedProgressMeter(nsIFrame* aFrame, int aWidgetType,
   bool indeterminate = IsIndeterminateProgress(parentFrame, eventStates);
   bool animate = indeterminate;
 
-  if (IsVistaOrLater()) {
-    // Vista and up progress meter is fill style, rendered here. We render
-    // the pulse overlay in the follow up section below.
-    DrawThemeBackground(aTheme, aHdc, aPart, aState,
-                        &adjWidgetRect, &adjClipRect);
-    if (!IsProgressMeterFilled(aFrame)) {
-      animate = true;
-    }
-  } else if (!indeterminate) {
-    // XP progress meters are 'chunk' style.
-    DrawChunkProgressMeter(aTheme, aHdc, aPart, aState, aFrame,
-                           &adjWidgetRect, &adjClipRect, aAppUnits,
-                           indeterminate, vertical, IsFrameRTL(aFrame));
-  }    
+  // Vista and up progress meter is fill style, rendered here. We render
+  // the pulse overlay in the follow up section below.
+  DrawThemeBackground(aTheme, aHdc, aPart, aState,
+                      &adjWidgetRect, &adjClipRect);
+  if (!IsProgressMeterFilled(aFrame)) {
+    animate = true;
+  }
 
   if (animate) {
     // Indeterminate rendering
@@ -706,14 +582,8 @@ nsNativeThemeWin::DrawThemedProgressMeter(nsIFrame* aFrame, int aWidgetType,
     RECT overlayRect =
       CalculateProgressOverlayRect(aFrame, &adjWidgetRect, vertical,
                                    indeterminate, false);
-    if (IsVistaOrLater()) {
-      DrawThemeBackground(aTheme, aHdc, overlayPart, aState, &overlayRect,
-                          &adjClipRect);
-    } else {
-      DrawChunkProgressMeter(aTheme, aHdc, overlayPart, aState, aFrame,
-                             &overlayRect, &adjClipRect, aAppUnits,
-                             indeterminate, vertical, IsFrameRTL(aFrame));
-    }
+    DrawThemeBackground(aTheme, aHdc, overlayPart, aState, &overlayRect,
+                        &adjClipRect);
 
     if (!QueueAnimatedContentForRefresh(aFrame->GetContent(), 60)) {
       NS_WARNING("unable to animate progress widget!");
@@ -724,15 +594,6 @@ nsNativeThemeWin::DrawThemedProgressMeter(nsIFrame* aFrame, int aWidgetType,
 HANDLE
 nsNativeThemeWin::GetTheme(uint8_t aWidgetType)
 { 
-  if (!IsVistaOrLater()) {
-    // On XP or earlier, render dropdowns as textfields;
-    // doing it the right way works fine with the MS themes,
-    // but breaks on a lot of custom themes (presumably because MS
-    // apps do the textfield border business as well).
-    if (aWidgetType == NS_THEME_MENULIST)
-      aWidgetType = NS_THEME_TEXTFIELD;
-  }
-
   switch (aWidgetType) {
     case NS_THEME_BUTTON:
     case NS_THEME_RADIO:
@@ -745,9 +606,7 @@ nsNativeThemeWin::GetTheme(uint8_t aWidgetType)
     case NS_THEME_FOCUS_OUTLINE:
       return nsUXThemeData::GetTheme(eUXEdit);
     case NS_THEME_TOOLTIP:
-      // XP/2K3 should force a classic treatment of tooltips
-      return !IsVistaOrLater() ?
-        nullptr : nsUXThemeData::GetTheme(eUXTooltip);
+      return nsUXThemeData::GetTheme(eUXTooltip);
     case NS_THEME_TOOLBOX:
       return nsUXThemeData::GetTheme(eUXRebar);
     case NS_THEME_WIN_MEDIA_TOOLBOX:
@@ -874,12 +733,6 @@ nsresult
 nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType, 
                                        int32_t& aPart, int32_t& aState)
 {
-  if (!IsVistaOrLater()) {
-    // See GetTheme
-    if (aWidgetType == NS_THEME_MENULIST)
-      aWidgetType = NS_THEME_TEXTFIELD;
-  }
-
   switch (aWidgetType) {
     case NS_THEME_BUTTON: {
       aPart = BP_BUTTON;
@@ -952,63 +805,43 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
     case NS_THEME_TEXTFIELD_MULTILINE: {
       EventStates eventState = GetContentState(aFrame, aWidgetType);
 
-      if (IsVistaOrLater()) {
-        /* Note: the NOSCROLL type has a rounded corner in each
-         * corner.  The more specific HSCROLL, VSCROLL, HVSCROLL types
-         * have side and/or top/bottom edges rendered as straight
-         * horizontal lines with sharp corners to accommodate a
-         * scrollbar.  However, the scrollbar gets rendered on top of
-         * this for us, so we don't care, and can just use NOSCROLL
-         * here.
-         */
-        aPart = TFP_EDITBORDER_NOSCROLL;
-
-        if (!aFrame) {
-          aState = TFS_EDITBORDER_NORMAL;
-        } else if (IsDisabled(aFrame, eventState)) {
-          aState = TFS_EDITBORDER_DISABLED;
-        } else if (IsReadOnly(aFrame)) {
-          /* no special read-only state */
-          aState = TFS_EDITBORDER_NORMAL;
-        } else {
-          nsIContent* content = aFrame->GetContent();
+      /* Note: the NOSCROLL type has a rounded corner in each corner.  The more
+       * specific HSCROLL, VSCROLL, HVSCROLL types have side and/or top/bottom
+       * edges rendered as straight horizontal lines with sharp corners to
+       * accommodate a scrollbar.  However, the scrollbar gets rendered on top
+       * of this for us, so we don't care, and can just use NOSCROLL here.
+       */
+      aPart = TFP_EDITBORDER_NOSCROLL;
 
-          /* XUL textboxes don't get focused themselves, because they have child
-           * html:input.. but we can check the XUL focused attributes on them
-           */
-          if (content && content->IsXULElement() && IsFocused(aFrame))
-            aState = TFS_EDITBORDER_FOCUSED;
-          else if (eventState.HasAtLeastOneOfStates(NS_EVENT_STATE_ACTIVE | NS_EVENT_STATE_FOCUS))
-            aState = TFS_EDITBORDER_FOCUSED;
-          else if (eventState.HasState(NS_EVENT_STATE_HOVER))
-            aState = TFS_EDITBORDER_HOVER;
-          else
-            aState = TFS_EDITBORDER_NORMAL;
-        }
+      if (!aFrame) {
+        aState = TFS_EDITBORDER_NORMAL;
+      } else if (IsDisabled(aFrame, eventState)) {
+        aState = TFS_EDITBORDER_DISABLED;
+      } else if (IsReadOnly(aFrame)) {
+        /* no special read-only state */
+        aState = TFS_EDITBORDER_NORMAL;
       } else {
-        aPart = TFP_TEXTFIELD;
-        
-        if (!aFrame)
-          aState = TS_NORMAL;
-        else if (IsDisabled(aFrame, eventState))
-          aState = TS_DISABLED;
-        else if (IsReadOnly(aFrame))
-          aState = TFS_READONLY;
+        nsIContent* content = aFrame->GetContent();
+
+        /* XUL textboxes don't get focused themselves, because they have child
+         * html:input.. but we can check the XUL focused attributes on them
+         */
+        if (content && content->IsXULElement() && IsFocused(aFrame))
+          aState = TFS_EDITBORDER_FOCUSED;
+        else if (eventState.HasAtLeastOneOfStates(NS_EVENT_STATE_ACTIVE | NS_EVENT_STATE_FOCUS))
+          aState = TFS_EDITBORDER_FOCUSED;
+        else if (eventState.HasState(NS_EVENT_STATE_HOVER))
+          aState = TFS_EDITBORDER_HOVER;
         else
-          aState = StandardGetState(aFrame, aWidgetType, true);
+          aState = TFS_EDITBORDER_NORMAL;
       }
 
       return NS_OK;
     }
     case NS_THEME_FOCUS_OUTLINE: {
-      if (IsVistaOrLater()) {
-        // XXX the EDITBORDER values don't respect DTBG_OMITCONTENT
-        aPart = TFP_TEXTFIELD; //TFP_EDITBORDER_NOSCROLL;
-        aState = TS_FOCUSED; //TFS_EDITBORDER_FOCUSED;
-      } else {
-        aPart = TFP_TEXTFIELD;
-        aState = TS_FOCUSED;
-      }
+      // XXX the EDITBORDER values don't respect DTBG_OMITCONTENT
+      aPart = TFP_TEXTFIELD; //TFP_EDITBORDER_NOSCROLL;
+      aState = TS_FOCUSED; //TFS_EDITBORDER_FOCUSED;
       return NS_OK;
     }
     case NS_THEME_TOOLTIP: {
@@ -1032,11 +865,9 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
       nsIFrame* parentFrame = aFrame->GetParent();
       if (aWidgetType == NS_THEME_PROGRESSCHUNK_VERTICAL ||
           IsVerticalProgress(parentFrame)) {
-        aPart = IsVistaOrLater() ?
-          PP_FILLVERT : PP_CHUNKVERT;
+        aPart = PP_FILLVERT;
       } else {
-        aPart = IsVistaOrLater() ?
-          PP_FILL : PP_CHUNK;
+        aPart = PP_FILL;
       }
 
       aState = PBBVS_NORMAL;
@@ -1100,8 +931,7 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
           aState += TS_ACTIVE;
         else if (eventState.HasState(NS_EVENT_STATE_HOVER))
           aState += TS_HOVER;
-        else if (IsVistaOrLater() &&
-                 parentState.HasState(NS_EVENT_STATE_HOVER))
+        else if (parentState.HasState(NS_EVENT_STATE_HOVER))
           aState = (aWidgetType - NS_THEME_SCROLLBARBUTTON_UP) + SP_BUTTON_IMPLICIT_HOVER_BASE;
         else
           aState += TS_NORMAL;
@@ -1204,14 +1034,7 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
     case NS_THEME_SCROLLBAR:
     case NS_THEME_SCROLLBAR_SMALL: {
       aState = 0;
-      if (IsVistaOrLater()) {
-        // On vista, they have a part
-        aPart = RP_BACKGROUND;
-      } else {
-        // Otherwise, they don't.  (But I bet
-        // RP_BACKGROUND would work here, too);
-        aPart = 0;
-      }
+      aPart = RP_BACKGROUND;
       return NS_OK;
     }
     case NS_THEME_TOOLBAR: {
@@ -1336,8 +1159,7 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
         aFrame = parentFrame;
 
       EventStates eventState = GetContentState(aFrame, aWidgetType);
-      aPart = IsVistaOrLater() ?
-        CBP_DROPMARKER_VISTA : CBP_DROPMARKER;
+      aPart = CBP_DROPMARKER_VISTA;
 
       // For HTML controls with author styling, we should fall
       // back to the old dropmarker style to avoid clashes with
@@ -1357,28 +1179,25 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
       else
         isOpen = IsOpenButton(aFrame);
 
-      if (IsVistaOrLater()) {
-        if (isHTML || IsMenuListEditable(aFrame)) {
-          if (isOpen) {
-            /* Hover is propagated, but we need to know whether we're
-             * hovering just the combobox frame, not the dropdown frame.
-             * But, we can't get that information, since hover is on the
-             * content node, and they share the same content node.  So,
-             * instead, we cheat -- if the dropdown is open, we always
-             * show the hover state.  This looks fine in practice.
-             */
-            aState = TS_HOVER;
-            return NS_OK;
-          }
-        } else {
-          /* On Vista, the dropdown indicator on a menulist button in  
-           * chrome is not given a hover effect. When the frame isn't
-           * isn't HTML content, we cheat and force the dropdown state
-           * to be normal. (Bug 430434)
+      if (isHTML || IsMenuListEditable(aFrame)) {
+        if (isOpen) {
+          /* Hover is propagated, but we need to know whether we're hovering
+           * just the combobox frame, not the dropdown frame. But, we can't get
+           * that information, since hover is on the content node, and they
+           * share the same content node.  So, instead, we cheat -- if the
+           * dropdown is open, we always show the hover state.  This looks fine
+           * in practice.
            */
-          aState = TS_NORMAL;
+          aState = TS_HOVER;
           return NS_OK;
         }
+      } else {
+        /* The dropdown indicator on a menulist button in chrome is not given a
+         * hover effect. When the frame isn't isn't HTML content, we cheat and
+         * force the dropdown state to be normal. (Bug 430434)
+         */
+        aState = TS_NORMAL;
+        return NS_OK;
       }
 
       aState = TS_NORMAL;
@@ -1879,7 +1698,7 @@ RENDER_AGAIN:
   else if (aWidgetType == NS_THEME_PROGRESSCHUNK ||
            aWidgetType == NS_THEME_PROGRESSCHUNK_VERTICAL) {
     DrawThemedProgressMeter(aFrame, aWidgetType, theme, hdc, part, state,
-                            &widgetRect, &clipRect, p2a);
+                            &widgetRect, &clipRect);
   }
   else if (aWidgetType == NS_THEME_FOCUS_OUTLINE) {
     // Inflate 'widgetRect' with the focus outline size.
@@ -2145,41 +1964,39 @@ nsNativeThemeWin::GetWidgetPadding(nsDeviceContext* aContext,
     return ok;
   }
 
-  if (IsVistaOrLater()) {
-    if (aWidgetType == NS_THEME_NUMBER_INPUT ||
-        aWidgetType == NS_THEME_TEXTFIELD ||
-        aWidgetType == NS_THEME_TEXTFIELD_MULTILINE ||
-        aWidgetType == NS_THEME_MENULIST)
-    {
-      /* If we have author-specified padding for these elements, don't do the fixups below */
-      if (aFrame->PresContext()->HasAuthorSpecifiedRules(aFrame, NS_AUTHOR_SPECIFIED_PADDING))
-        return false;
-    }
+  if (aWidgetType == NS_THEME_NUMBER_INPUT ||
+      aWidgetType == NS_THEME_TEXTFIELD ||
+      aWidgetType == NS_THEME_TEXTFIELD_MULTILINE ||
+      aWidgetType == NS_THEME_MENULIST)
+  {
+    // If we have author-specified padding for these elements, don't do the
+    // fixups below.
+    if (aFrame->PresContext()->HasAuthorSpecifiedRules(aFrame, NS_AUTHOR_SPECIFIED_PADDING))
+      return false;
+  }
 
-    /* textfields need extra pixels on all sides, otherwise they
-     * wrap their content too tightly.  The actual border is drawn 1px
-     * inside the specified rectangle, so Gecko will end up making the
-     * contents look too small.  Instead, we add 2px padding for the
-     * contents and fix this. (Used to be 1px added, see bug 430212)
+  /* textfields need extra pixels on all sides, otherwise they wrap their
+   * content too tightly.  The actual border is drawn 1px inside the specified
+   * rectangle, so Gecko will end up making the contents look too small.
+   * Instead, we add 2px padding for the contents and fix this. (Used to be 1px
+   * added, see bug 430212)
+   */
+  if (aWidgetType == NS_THEME_NUMBER_INPUT ||
+      aWidgetType == NS_THEME_TEXTFIELD ||
+      aWidgetType == NS_THEME_TEXTFIELD_MULTILINE) {
+    aResult->top = aResult->bottom = 2;
+    aResult->left = aResult->right = 2;
+    ScaleForFrameDPI(aResult, aFrame);
+    return ok;
+  } else if (IsHTMLContent(aFrame) && aWidgetType == NS_THEME_MENULIST) {
+    /* For content menulist controls, we need an extra pixel so that we have
+     * room to draw our focus rectangle stuff. Otherwise, the focus rect might
+     * overlap the control's border.
      */
-    if (aWidgetType == NS_THEME_NUMBER_INPUT ||
-        aWidgetType == NS_THEME_TEXTFIELD ||
-        aWidgetType == NS_THEME_TEXTFIELD_MULTILINE) {
-      aResult->top = aResult->bottom = 2;
-      aResult->left = aResult->right = 2;
-      ScaleForFrameDPI(aResult, aFrame);
-      return ok;
-    } else if (IsHTMLContent(aFrame) && aWidgetType == NS_THEME_MENULIST) {
-      /* For content menulist controls, we need an extra pixel so
-       * that we have room to draw our focus rectangle stuff.
-       * Otherwise, the focus rect might overlap the control's
-       * border.
-       */
-      aResult->top = aResult->bottom = 1;
-      aResult->left = aResult->right = 1;
-      ScaleForFrameDPI(aResult, aFrame);
-      return ok;
-    }
+    aResult->top = aResult->bottom = 1;
+    aResult->left = aResult->right = 1;
+    ScaleForFrameDPI(aResult, aFrame);
+    return ok;
   }
 
   int32_t right, left, top, bottom;
@@ -2244,23 +2061,21 @@ nsNativeThemeWin::GetWidgetOverflow(nsDeviceContext* aContext,
    * a border only shows up if the widget is being hovered.
    */
 #if 0
-  if (IsVistaOrLater()) {
-    /* We explicitly draw dropdown buttons in HTML content 1px bigger
-     * up, right, and bottom so that they overlap the dropdown's border
-     * like they're supposed to.
-     */
-    if (aWidgetType == NS_THEME_MENULIST_BUTTON &&
-        IsHTMLContent(aFrame) &&
-        !IsWidgetStyled(aFrame->GetParent()->PresContext(),
-                        aFrame->GetParent(),
-                        NS_THEME_MENULIST))
-    {
-      int32_t p2a = aContext->AppUnitsPerDevPixel();
-      /* Note: no overflow on the left */
-      nsMargin m(p2a, p2a, p2a, 0);
-      aOverflowRect->Inflate (m);
-      return true;
-    }
+  /* We explicitly draw dropdown buttons in HTML content 1px bigger up, right,
+   * and bottom so that they overlap the dropdown's border like they're
+   * supposed to.
+   */
+  if (aWidgetType == NS_THEME_MENULIST_BUTTON &&
+      IsHTMLContent(aFrame) &&
+      !IsWidgetStyled(aFrame->GetParent()->PresContext(),
+                      aFrame->GetParent(),
+                      NS_THEME_MENULIST))
+  {
+    int32_t p2a = aContext->AppUnitsPerDevPixel();
+    /* Note: no overflow on the left */
+    nsMargin m(p2a, p2a, p2a, 0);
+    aOverflowRect->Inflate (m);
+    return true;
   }
 #endif
 
@@ -2384,22 +2199,18 @@ nsNativeThemeWin::GetMinimumWidgetSize(nsPresContext* aPresContext, nsIFrame* aF
     case NS_THEME_SCALETHUMB_VERTICAL:
     {
       *aIsOverridable = false;
-      // on Vista, GetThemePartAndState returns odd values for
+      // On Vista, GetThemePartAndState returns odd values for
       // scale thumbs, so use a hardcoded size instead.
-      if (IsVistaOrLater()) {
-        if (aWidgetType == NS_THEME_SCALETHUMB_HORIZONTAL ||
-            (aWidgetType == NS_THEME_RANGE_THUMB && IsRangeHorizontal(aFrame))) {
-          aResult->width = 12;
-          aResult->height = 20;
-        }
-        else {
-          aResult->width = 20;
-          aResult->height = 12;
-        }
-        ScaleForFrameDPI(aResult, aFrame);
-        return rv;
+      if (aWidgetType == NS_THEME_SCALETHUMB_HORIZONTAL ||
+          (aWidgetType == NS_THEME_RANGE_THUMB && IsRangeHorizontal(aFrame))) {
+        aResult->width = 12;
+        aResult->height = 20;
+      } else {
+        aResult->width = 20;
+        aResult->height = 12;
       }
-      break;
+      ScaleForFrameDPI(aResult, aFrame);
+      return rv;
     }
 
     case NS_THEME_SCROLLBAR:
@@ -2438,11 +2249,6 @@ nsNativeThemeWin::GetMinimumWidgetSize(nsPresContext* aPresContext, nsIFrame* aF
       // stores that info in nsUXThemeData.
       aResult->width = nsUXThemeData::sCommandButtons[CMDBUTTONIDX_RESTORE].cx;
       aResult->height = nsUXThemeData::sCommandButtons[CMDBUTTONIDX_RESTORE].cy;
-      // For XP, subtract 4 from system metrics dimensions.
-      if (!IsVistaOrLater()) {
-        aResult->width -= 4;
-        aResult->height -= 4;
-      }
       AddPaddingRect(aResult, CAPTIONBUTTON_RESTORE);
       *aIsOverridable = false;
       return rv;
@@ -2450,10 +2256,6 @@ nsNativeThemeWin::GetMinimumWidgetSize(nsPresContext* aPresContext, nsIFrame* aF
     case NS_THEME_WINDOW_BUTTON_MINIMIZE:
       aResult->width = nsUXThemeData::sCommandButtons[CMDBUTTONIDX_MINIMIZE].cx;
       aResult->height = nsUXThemeData::sCommandButtons[CMDBUTTONIDX_MINIMIZE].cy;
-      if (!IsVistaOrLater()) {
-        aResult->width -= 4;
-        aResult->height -= 4;
-      }
       AddPaddingRect(aResult, CAPTIONBUTTON_MINIMIZE);
       *aIsOverridable = false;
       return rv;
@@ -2461,10 +2263,6 @@ nsNativeThemeWin::GetMinimumWidgetSize(nsPresContext* aPresContext, nsIFrame* aF
     case NS_THEME_WINDOW_BUTTON_CLOSE:
       aResult->width = nsUXThemeData::sCommandButtons[CMDBUTTONIDX_CLOSE].cx;
       aResult->height = nsUXThemeData::sCommandButtons[CMDBUTTONIDX_CLOSE].cy;
-      if (!IsVistaOrLater()) {
-        aResult->width -= 4;
-        aResult->height -= 4;
-      }
       AddPaddingRect(aResult, CAPTIONBUTTON_CLOSE);
       *aIsOverridable = false;
       return rv;
@@ -2594,18 +2392,9 @@ nsNativeThemeWin::WidgetStateChanged(nsIFrame* aFrame, uint8_t aWidgetType,
     return NS_OK;
   }
 
-  // On Vista, the scrollbar buttons need to change state when the track has/doesn't have hover
-  if (!IsVistaOrLater() &&
-      (aWidgetType == NS_THEME_SCROLLBAR_VERTICAL || 
-      aWidgetType == NS_THEME_SCROLLBAR_HORIZONTAL)) {
-    *aShouldRepaint = false;
-    return NS_OK;
-  }
-
   // We need to repaint the dropdown arrow in vista HTML combobox controls when
   // the control is closed to get rid of the hover effect.
-  if (IsVistaOrLater() &&
-      (aWidgetType == NS_THEME_MENULIST || aWidgetType == NS_THEME_MENULIST_BUTTON) &&
+  if ((aWidgetType == NS_THEME_MENULIST || aWidgetType == NS_THEME_MENULIST_BUTTON) &&
       IsHTMLContent(aFrame))
   {
     *aShouldRepaint = true;
diff --git a/widget/windows/nsNativeThemeWin.h b/widget/windows/nsNativeThemeWin.h
index f206494447..32b82b1e11 100644
--- a/widget/windows/nsNativeThemeWin.h
+++ b/widget/windows/nsNativeThemeWin.h
@@ -117,8 +117,7 @@ protected:
   void DrawThemedProgressMeter(nsIFrame* aFrame, int aWidgetType,
                                HANDLE aTheme, HDC aHdc,
                                int aPart, int aState,
-                               RECT* aWidgetRect, RECT* aClipRect,
-                               gfxFloat aAppUnits);
+                               RECT* aWidgetRect, RECT* aClipRect);
 
 private:
   TimeStamp mProgressDeterminateTimeStamp;
diff --git a/widget/windows/nsUXThemeConstants.h b/widget/windows/nsUXThemeConstants.h
index 731dcedf25..ba7afde821 100644
--- a/widget/windows/nsUXThemeConstants.h
+++ b/widget/windows/nsUXThemeConstants.h
@@ -67,7 +67,7 @@
 #define SP_GRIPPERHOR      8
 #define SP_GRIPPERVERT     9
 
-// Vista only; implict hover state.
+// Implicit hover state.
 // BASE + 0 = UP, + 1 = DOWN, etc.
 #define SP_BUTTON_IMPLICIT_HOVER_BASE   17
 
diff --git a/widget/windows/nsUXThemeData.cpp b/widget/windows/nsUXThemeData.cpp
index bcbd32484c..4d9ac95708 100644
--- a/widget/windows/nsUXThemeData.cpp
+++ b/widget/windows/nsUXThemeData.cpp
@@ -143,10 +143,8 @@ nsUXThemeData::InitTitlebarInfo()
   sCommandButtons[3].cx = sCommandButtons[0].cx * 3;
   sCommandButtons[3].cy = sCommandButtons[0].cy;
 
-  // Use system metrics for pre-vista, otherwise trigger a
-  // refresh on the next layout.
-  sTitlebarInfoPopulatedAero = sTitlebarInfoPopulatedThemed =
-    !IsVistaOrLater();
+  // Trigger a refresh on the next layout.
+  sTitlebarInfoPopulatedAero = sTitlebarInfoPopulatedThemed = false;
 }
 
 // static
@@ -306,7 +304,7 @@ void
 nsUXThemeData::UpdateNativeThemeInfo()
 {
   // Trigger a refresh of themed button metrics if needed
-  sTitlebarInfoPopulatedThemed = !IsVistaOrLater();
+  sTitlebarInfoPopulatedThemed = false;
 
   sIsDefaultWindowsTheme = false;
   sThemeId = LookAndFeel::eWindowsTheme_Generic;
diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index a8923f78e3..b2bb59bd36 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -266,8 +266,7 @@ LONG            nsWindow::sLastMouseDownTime      = 0L;
 LONG            nsWindow::sLastClickCount         = 0L;
 BYTE            nsWindow::sLastMouseButton        = 0;
 
-// Trim heap on minimize. (initialized, but still true.)
-int             nsWindow::sTrimOnMinimize         = 2;
+bool            nsWindow::sHaveInitializedPrefs   = false;
 
 TriStateBool nsWindow::sHasBogusPopupsDropShadowOnMultiMonitor = TRI_UNKNOWN;
 
@@ -783,7 +782,7 @@ nsWindow::Create(nsIWidget* aParent,
       parent = nullptr;
     }
 
-    if (IsVistaOrLater() && !IsWin8OrLater() &&
+    if (!IsWin8OrLater() &&
         HasBogusPopupsDropShadowOnMultiMonitor()) {
       extendedStyle |= WS_EX_COMPOSITED;
     }
@@ -908,20 +907,13 @@ nsWindow::Create(nsIWidget* aParent,
   mDefaultIMC.Init(this);
   IMEHandler::InitInputContext(this, mInputContext);
 
-  // If the internal variable set by the config.trim_on_minimize pref has not
-  // been initialized, and if this is the hidden window (conveniently created
-  // before any visible windows, and after the profile has been initialized),
-  // do some initialization work.
-  if (sTrimOnMinimize == 2 && mWindowType == eWindowType_invisible) {
-    // Our internal trim prevention logic is effective on 2K/XP at maintaining
-    // the working set when windows are minimized, but on Vista and up it has
-    // little to no effect. Since this feature has been the source of numerous
-    // bugs over the years, disable it (sTrimOnMinimize=1) on Vista and up.
-    sTrimOnMinimize =
-      Preferences::GetBool("config.trim_on_minimize",
-        IsVistaOrLater() ? 1 : 0);
+  // Do some initialization work, but only if (a) it hasn't already been done,
+  // and (b) this is the hidden window (which is conveniently created before
+  // any visible windows but after the profile has been initialized).
+  if (!sHaveInitializedPrefs && mWindowType == eWindowType_invisible) {
     sSwitchKeyboardLayout =
       Preferences::GetBool("intl.keyboard.per_window_layout", false);
+    sHaveInitializedPrefs = true;
   }
 
   // Query for command button metric data for rendering the titlebar. We
@@ -1647,9 +1639,10 @@ bool nsWindow::IsVisible() const
 
 // XP and Vista visual styles sometimes require window clipping regions to be applied for proper
 // transparency. These routines are called on size and move operations.
+// XXX this is apparently still needed in Windows 7 and later
 void nsWindow::ClearThemeRegion()
 {
-  if (IsVistaOrLater() && !HasGlass() &&
+  if (!HasGlass() &&
       (mWindowType == eWindowType_popup && !IsPopupWithTitleBar() &&
        (mPopupType == ePopupTypeTooltip || mPopupType == ePopupTypePanel))) {
     SetWindowRgn(mWnd, nullptr, false);
@@ -1663,7 +1656,7 @@ void nsWindow::SetThemeRegion()
   // so default constants are used for part and state. At some point we might need part and
   // state values from nsNativeThemeWin's GetThemePartAndState, but currently windows that
   // change shape based on state haven't come up.
-  if (IsVistaOrLater() && !HasGlass() &&
+  if (!HasGlass() &&
       (mWindowType == eWindowType_popup && !IsPopupWithTitleBar() &&
        (mPopupType == ePopupTypeTooltip || mPopupType == ePopupTypePanel))) {
     HRGN hRgn = nullptr;
@@ -2080,13 +2073,7 @@ nsWindow::SetSizeMode(nsSizeMode aMode)
         break;
 
       case nsSizeMode_Minimized :
-        // Using SW_SHOWMINIMIZED prevents the working set from being trimmed but
-        // keeps the window active in the tray. So after the window is minimized,
-        // windows will fire WM_WINDOWPOSCHANGED (OnWindowPosChanged) at which point
-        // we will do some additional processing to get the active window set right.
-        // If sTrimOnMinimize is set, we let windows handle minimization normally
-        // using SW_MINIMIZE.
-        mode = sTrimOnMinimize ? SW_MINIMIZE : SW_SHOWMINIMIZED;
+        mode = SW_MINIMIZE;
         break;
 
       default :
@@ -5828,12 +5815,6 @@ nsWindow::ProcessMessage(UINT msg, WPARAM& wParam, LPARAM& lParam,
     case WM_SYSCOMMAND:
     {
       WPARAM filteredWParam = (wParam &0xFFF0);
-      // prevent Windows from trimming the working set. bug 76831
-      if (!sTrimOnMinimize && filteredWParam == SC_MINIMIZE) {
-        ::ShowWindow(mWnd, SW_SHOWMINIMIZED);
-        result = true;
-      }
-
       if (mSizeMode == nsSizeMode_Fullscreen &&
           filteredWParam == SC_RESTORE &&
           GetCurrentShowCmd(mWnd) != SW_SHOWMINIMIZED) {
@@ -6451,14 +6432,6 @@ void nsWindow::OnWindowPosChanged(WINDOWPOS* wp)
     else
       mSizeMode = nsSizeMode_Normal;
 
-    // If !sTrimOnMinimize, we minimize windows using SW_SHOWMINIMIZED (See
-    // SetSizeMode for internal calls, and WM_SYSCOMMAND for external). This
-    // prevents the working set from being trimmed but keeps the window active.
-    // After the window is minimized, we need to do some touch up work on the
-    // active window. (bugs 76831 & 499816)
-    if (!sTrimOnMinimize && nsSizeMode_Minimized == mSizeMode)
-      ActivateOtherWindowHelper(mWnd);
-
 #ifdef WINSTATE_DEBUG_OUTPUT
     switch (mSizeMode) {
       case nsSizeMode_Normal:
@@ -6579,31 +6552,6 @@ void nsWindow::OnWindowPosChanged(WINDOWPOS* wp)
   }
 }
 
-// static
-void nsWindow::ActivateOtherWindowHelper(HWND aWnd)
-{
-  // Find the next window that is enabled, visible, and not minimized.
-  HWND hwndBelow = ::GetNextWindow(aWnd, GW_HWNDNEXT);
-  while (hwndBelow && (!::IsWindowEnabled(hwndBelow) || !::IsWindowVisible(hwndBelow) ||
-                       ::IsIconic(hwndBelow))) {
-    hwndBelow = ::GetNextWindow(hwndBelow, GW_HWNDNEXT);
-  }
-
-  // Push ourselves to the bottom of the stack, then activate the
-  // next window.
-  ::SetWindowPos(aWnd, HWND_BOTTOM, 0, 0, 0, 0,
-                 SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE);
-  if (hwndBelow)
-    ::SetForegroundWindow(hwndBelow);
-
-  // Play the minimize sound while we're here, since that is also
-  // forgotten when we use SW_SHOWMINIMIZED.
-  nsCOMPtr<nsISound> sound(do_CreateInstance("@mozilla.org/sound;1"));
-  if (sound) {
-    sound->PlaySystemSound(NS_LITERAL_STRING("Minimize"));
-  }
-}
-
 void nsWindow::OnWindowPosChanging(LPWINDOWPOS& info)
 {
   // Update non-client margins if the frame size is changing, and let the
diff --git a/widget/windows/nsWindow.h b/widget/windows/nsWindow.h
index 248978bd79..199500e9c5 100644
--- a/widget/windows/nsWindow.h
+++ b/widget/windows/nsWindow.h
@@ -486,7 +486,6 @@ protected:
                                               bool aIntersectWithExisting) override;
   nsIntRegion             GetRegionToPaint(bool aForceFullRepaint,
                                            PAINTSTRUCT ps, HDC aDC);
-  static void             ActivateOtherWindowHelper(HWND aWnd);
   void                    ClearCachedResources();
   nsIWidgetListener*      GetPaintListener();
 
@@ -552,7 +551,7 @@ protected:
   static bool           sJustGotDeactivate;
   static bool           sJustGotActivate;
   static bool           sIsInMouseCapture;
-  static int            sTrimOnMinimize;
+  static bool           sHaveInitializedPrefs;
 
   // Always use the helper method to read this property.  See bug 603793.
   static TriStateBool   sHasBogusPopupsDropShadowOnMultiMonitor;