How to disable Firefox un-maximizing window via double clicking the tab toolbar?

Double clicking the tab toolbar (or any other toolbars) results in Firefox widow being restored (un-maximized). This is driving a lot of people nuts because they accidentally double click the toolbars. My own mouse has to be replaced because it’s bugging out double-clicking for single clicks.

How do we disable Firefox from changing the window size when the toolbars are double-clicked?