wxWidgets is a cross platform library that has bindings to GTK so it can run on GTK systems (this is what wxGTK is). It has other bindings too, like wxMSW for Win32, which I would expect to be faster than GTK on Win32. I would recommend starting with wxWidgets (or wxPython (http://www.wxpython.org
) if you know python - it's much easier to mess around with small python scripts while you get to grips with the way the toolkit works). The documentation seems very thorough, but I haven't seen much in the way of good tutorials - the best thing is to check out the demo apps that come with it.