>"No external C/C++ library dependencies" is simply impossible. Given that the host OS is not implemented in Python, some kind of bridge to its native libraries is necessary for a GUI library.
Not true. Python provides facilities for dealing with dynamic link libraries from native Python code. These can be used to interface with the OS directly, without necessitating writing a C/C++ wrapper.
OK then it's a terminological confusion, because I would say that gives you a dependency on said "dynamic link libraries". Whether you need to write a C/C++ wrapper only determines if the dependency is in runtime or also compile time.
On Windows or Mac this may be true, but with Linux the GTK or Qt libraries are not part of the OS, but are used in desktop environments which may or may not be installed, and there are different version etc. so things are more messy and it's definitely a dependency which has to be fulfilled (at least at runtime).
