One problem. When the address bar is white that is when the address bar has a white background, the pen symbol does not show at all because the pen symbol you use is white (as I assume you use a dark background that has a black address bar so you need a white pen to see it).

You seem to have done your pen in the address bar only when the address bar has a black background.

BUT you forgot to do it for when the address bar has a white background and, in such a case, the pen should show only if the pen is black in this second case; in my case, it only shows a full white space on my address bar instead of a space showing a black pen, as it shows a white space and your white pen but because your pen is white, it ends up showing only a white space.

Moreover, it would be better to allow an icon of your addon to be pinned to the toolbar instead of using a full space on the address bar for every single tab, as I have to change the name of the tab extremely rarely.

Especially considering the fact that your space on my address bar (that has a white background) shows only as a white space without displaying at all a black pen because you created only a white pen for your address bar that has a black background.

Thanks to correct this issue if you can. And thanks to the developer for this addon.