I was going to post one myself but searched and found this one.

It would be very very handy to have a simple search bar at the top of the extension dropdown menu, because over time people add a lof of different extensions to their firefox and it becomes very very very tedious to always manually search for the one that I need right now.
So just a simple searchbar at the top that filters extension in the dropdown menu by name would be awesome to have, so that I can quickly find and access its specific extension window.
Also make it so that the search bar is instantly focused when the extension menu pops up, so that the user can immediately start typing and the filtering begins. Then the user can just press enter to launch the extension window of the first element in the list. This would allow for a easy mouse-free keyboard-only navigation.
And before somebody asks: I do not want pin every extension to the toolbar just to quickly access it, it would like to hide away most of them in the dropdown menu instead, so this is not a viable option.