This add-on works great. The only issue is one that isn't the fault of the add-on. I use a 4k 49" monitor, so I have plenty of real-estate. The popup size is limited to 800x600, which is a limitation of Firefox, not the add-on. Markus was very helpful in explaining this to me and suggesting a workaround. He said "You can open the tab manager in its' own tab however ( right click -> "Open in own tab" ). That would give you the fullscreen capacity that we're seeking..". I find it easiest to open a Firefox window just for Tab Manager Plus. Thank you for porting this great add-on to Firefox!