Yep after upgrade and going to Firefox 46 found trying to highlight text for copy and paste makes for unreadable selection.
Seems a theme breakage due to going Gtk 3.20
So found in this thread on arch.
A simple go into your home .config/gtk-3.0/settings.ini and change Breeze to breeze fixed the issue for me.
Maybe want to push this up the ladder as a fix?
As worked great for me and checked multiple sites and text highlighting.
The default for Rolling is already lower case breeze (Default) for gtk+3 and carbon-gtk for gtk+2.
Don’t know what to say except about the Capital “B” vs. lower-case b in settings.ini
As my settings are default and showing default. And showing Capital B in dropdown.
All I know changing that settings.ini from Breeze to breeze fixed my highlighting issue.
Sorry, my bad. We have this set to Default not Breeze. There is no such theme as lower case breeze, all of the upstream themes are capitalized. All that your hack does is force gtk3 to fall back to Adwaita, which is essentially what setting this to Default does.
So change the settings.ini back and just select default?
Nevermind seems system did it for me.
gtk-font-name=Roboto [Goog] Medium 8
Getting a tad confusing with the Gtk transition to Gtk 3