gazpacho (next generation GUI Design)

gazpacho allows you to create the Graphical User Interface (GUI) of 
your GTK+ program in a visual way. It started as a Glade-3 clone but 
now it is more complete and featured than its ancestor. It tries to 
be compatible with libglade but it can handle some widgets that still
lack support in libglade.

gazpacho depends on PyGTK and kiwi, both of which are available from
SlackBuilds.org.