Programmica
Programmica offers a number of tutorials which intend to be easy-to-use and comprehensive to newcomers using graphical toolkits such as GTK+, Qt, or Tk. All of the tutorials are available in the public domain and can be downloaded, shared, rehosted, and modified as needed.
Tutorial Date Source Formats
Python GTK+ 3 Tutorial 26/10/2018 Download PDF / EPUB / TEXT

Andrew Steele - andrew@andrewsteele.me.uk