Is there a GUI Builder for Code::Blocks, something like BOA for Python?
Greetings, Emir

No. You can build windows gui programs, but you have to do it manually or buy someone else's program that produces windows resource files. You could also use a different IDE/compiler, such as QT which contains gui guilder.

If you use wxWidgets with Code::Blocks there's a RAD/GUI plugin called wxSmith which gives you the ability to drag and drop wxwidgets controls onto a design view and the plugin will auto-generate some boiler-plate code for you. Very similar to using visual studio with MFC and Windows Forms applications.