GUI stuff with Python sucks just as much as it does with Ruby. I.e. if you want to do GUI, don't choose either of these languages.
GUI kind of works best with whatever language the platform for the GUI toolkit wants you to use, but a lot of the time C++ will be that language, competing with JavaScript. Every other language, almost always will end up having bindings, or some other sort of outsourcing mechanism to connect its runtime to either C++ or JavaScript. If you want to just deal with one language when working on a GUI project, it's best to just go with the one the target platform wants you to use.
GUI kind of works best with whatever language the platform for the GUI toolkit wants you to use, but a lot of the time C++ will be that language, competing with JavaScript. Every other language, almost always will end up having bindings, or some other sort of outsourcing mechanism to connect its runtime to either C++ or JavaScript. If you want to just deal with one language when working on a GUI project, it's best to just go with the one the target platform wants you to use.