I would suggest Ultimate++.
1. With Ultimate++ IDE (it's called TheIde) you don't need to worry about makefiles which is a lot of headache for beginners.
2. You wouldn't believe how much faster it compiles than any other toolkit or IDE because of BLITZ technology.
3. Also learning and programming process is faster because requires sometimes nearly half the code you would need with other toolkits.
4. Less headache where you keep your files - it has packages and assemblies.
5. With it you have got all-in-one. IDE, GUI toolkit, libraries with OpenGL, ODBC, MySQL, Oracle, XML, PDF export etc etc. Like a swiss knife for programming. You can compare it only to Microsoft's (tm) Visual Studio (or KDevelop maybe).
I've tried WideStudio (from Japan) but after too many crashes lost patience.
6. WxWidgets technology shares most of Windows MFC problems (you can google to find about them).
7. FOX toolkit was started to be easier and better than Qt... but it doesn't have IDE.
8. There is one of the best comparisons of GUI toolkits at commercial JX GUI toolkit
http://www.newplanetsoftware.com/jx/compare.php
but for some reasons they don't include Ultimate++!
9. Also with Ultimate++ you don't need to worry about if you use some code from it. It has free BSD licence. Just read the licences before you use it...
10. I've installed it on Arch Linux without pacman just by extracting the archive file from upp.sourceforge.net- it has no dependancies. You can build your packages this way for any desktop window manager I guess. I run them on KDE and Xfce4 or just plain X.