After (set (make-local-variable 'track-mouse) t), when I click anywhere in the buffer, track-mouse will be reset to nil.

Emacs 24.5 didn't do that. It breaks a tooltip system I have for coding in C++ : I alternate between typing, clicking and hovering over variables to get tooltips. I cannot debug track-mouse because it is in the C layer of Emacs, not in lisp.

Anyone can help ?