I just downloaded it and it compiled with 2 errors

Testing ./Widget/Position...failed (2/7)
Testing ./Widget/Window...failed (2/15)
Total tests passed:28, skipped:0, failed:2
[download]

BUT.... the examples run well, and the code is not that hard to understand. It looks like gtk2 programming, and the dependent libs are gtk2 on my linux box. I didn't see a drag-n-drop gui-designer. It looks like they make connecting to events and signals easier. I would say it looks very promising, but it has a drab look like Tk( although "looks" depend on how much you put into it).

Interested people should look at the code in the examples subdir......... the code looks like Gtk2.... I might borrow some of their examples and see if they run as pure Gtk2.