> I think, that  Gtk+ would be a good choice as a standard gui
   > toolkit for Rugy, because it is
   >
   > 1. open source
   > 2. quite easy
   > 3 . very powerful
   > 4. is currently also ported to windows

Windows support?

   > Qt is also a really great tool, bat I have read, that making
   > bindings to Gtk+ is easier (because it is writtin in C, not in C++)

The little I know about QT and Windows support is that it's not free....

The discussion of windows frameworks is interesting (seen this happening
many times). If you want full cross-platform, you need to do a standalone
version and it takes a long time and will be a constant struggle to
maintain. Using underlying structures work as long as the licensing schemes
are in place. However, if you want to look at problems using such systems
across multi-platforms, look at the misery with the earlier Java AWK.

I don't know of a good solution. I would go myself with a Flash-like system,
myself, because then you get the most flexibility you could ever imagine
concerning a 2D graphics system, and the Flash engine is kind of free now
(src code available from Macromedia). The reason I like Flash is that the
actual UI designers are very productive with Flash, they really like it, and
it has anything you with in 2D space, and it gives a good platform for new
UI designs that will break away from the current paradigms. Anyway, it's
just a wild card.

--Kent