Glade is a GUI builder for GTK+ and GNOME. It stores projects in an XML format and can generate C code from this meta-format. Additionally, the meta-format can be converted to other languages via modules. For example, glade-- can generate C++ code.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.
Projects created prior to GTK+ 2.16 are now by default horizontally oriented. Other remaining properties are now also sync'ed up at load time. Glitches with use-action-appearance at save time were fixed. Two crashes were fixed. Several other minor modifications were made.