BTW, if you're not writing a windowed app, and are only interested in the canvas, you might want to look at SDL. You didn't specify exactly what you were working on.

Soo...if you're writing a windowed "productivity" app, use QT.

If you're writing a custom-graphics heavy app like a game or maybe some sort of visualization tool, use SDL.
 

I am very leery of APIs. It takes a lot to sell me. I started using QT just before the move to QT4, and instantly fell in love. At this point, unless I'm writing a game, I won't even touch C++ without using QT.

QT is the most consistent, well-documented, and intuitive API I have ever used.