wxPython is a Python interface for wxWidgets, a popular open source GUI library. The code written in wxPython is portable across most major platforms, such as Windows, Linux, and macOS.

The wxPython interface is generally considered to be better than Tkinter at building complex GUIs, primarily because it has a large base of natively supported widgets. However, Tkinter supporters do contest this claim.

The wxWidgets interface was originally written in the C++ programming language. Hence, wxPython inherits a large portion of the complexity that is typical of C++ programs. wxPython provides a very large base of classes, and it often takes more code to produce the same interface than it would take in Tkinter. However, in exchange for this complexity, wxPython provides a larger base of built-in widgets than Tkinter offers. 

Owing to its inherent complexity, wxPython has seen the emergence of several GUI builder toolkits, such as wxGlade, wxFormBuilder, and wxDesigner. The wxPython installation comes with demo programs that can help you quickly get started with the toolkit. To download the toolkit, or for more information on wxPython, visit http://wxpython.org/.