On Chrome and Safari (on Mac OS), command-shift-N opens a new incognito/private window. And so sometimes when I want to open a private window on Firefox I used command-shift-N by mistake (when I should have used command-shift-P). On Firefox, command-shift-N reopens the most recently closed window, and quite often I had a lot of tabs in the window I last closed and Firefox would try to open all of them. This is kind of annoying.
Because of this I want to disable Recently Closed Windows or change its short cut key. I have tried the Menu Wizard add-on, but it doesn't seem to find this menu item. I assume that it's because it's dynamically created. Is there a way to do this?