There are many reasons for the numerous undocumented aspects in Matlab - this article explains them.
This article lists the different types of undocumented/unsupported/hidden aspects in Matlab
Undocumented Secrets of Matlab-Java Programming (ISBN 9781439869031) is a book dedicated to the integration of Matlab and Java.
The information of whether or not an axes is zoomed or panned can easily be inferred from an internal undocumented
Multi-line tooltips are very easy to set up, once you know your way around a few undocumented hiccups.