Am I allowed to use code::blocks for commercial programms?
I believe that the only restriction on the GPL is that if you develop a (presumably IDE) program by basing your source code on that of Code::Blocks, you would have to release the source code for your own IDE (keep in mind, this wouldn't prevent you from selling the binaries).
Other than that, it's an absolutely free tool, and you should be able to develop commercial, close-sourced software with it.