Hello!

I need to make a GUI for my application and I am not sure which toolkit I should use therefor.
My requirements:
- must run under windows and should run under linux
- making widgets should be easy (I need to make non-standard widgets)
- there should be a community or at least resources where I can read/ask specific questions.
- freeware (we have Qt4 in the office)

What would you recommend? GTK or Qt4? Or are there better things?
The GUI itself consists only of a main (dialog) window where the widgets are placed on.

Greetings,