I have two keyboard layouts installed: 1) US-English and 2) Czech UCW. The UCW keyboard provides only accented letters as long as caps-lock is held. E.g.
CapsLock+A types accented Á, while A types just normal A.
Alt+CapsLock provides the original caps lock.
In Gnome Tweaks:
Keyboard->Additional Layout Options->Switching to another layout "Caps Lock (while pressed), Alt+Caps Lock for the original Caps Lock action" is checked.
After upgrading from 16.04 to 18.04 (Unity->Gnome) the accented letters stopped working in some applications like Firefox, Thunderbird, LibreOffice. Whereas in other applications like Gnome Terminal or Gedit (native Gnome applications?) the accented letters still work fine.
After some investigation I found out that if the UCW keyboard (second layout) is selected in the selection on the top of the screen, the accented letters are typed by default and CapsLock switches to the EN layout in all applications. But not the other way around.
If I change the layout order: 1) CS-UCW keyboard, 2) English keyboard then the accented letter typing with caps-lock works in Thunderbird/Firefox/Office and not on terminal or Gedit. I.e. exactly the opposite way than before.
What is wrong? Can someone explain this beaviour? And more important: how can I get the keyboard switching working in all applications?
After some more investigation I found out that the issue is only related to Wayland! When selecting X at login the keyboard works in all applications.