If you want to access the source:
Hope to see: http://www.gtxbase.org/forums
If you develop for Windows, 2 installers have available:
Basic: To download only the content of t-gtk and the libraries compiled in harbour.
Full: Style suite that contains: MinGW, Harbour 3.1 (svn), GTK +, Glade, t-gtk and TDolphin!!!