Since I upgraded from to 18.04 I've had this problem (actually gnome apps) : Main windows unusable with weird main window. Changing from the theme (Ambiance) to any other theme (Adwaita, Numix, etc) solved the problem. (I'm using gnome shell)
Since I upgraded from to 18.04 I've had this problem (actually gnome apps) : Main windows unusable with weird main window.
Changing from the theme (Ambiance) to any other theme (Adwaita, Numix, etc) solved the problem.
(I'm using gnome shell)