Thanks. I will probably end up keep using gimp and krita.

Looks interesting, hadn’t heard from it. Thanks.

This does not remember the position of each individual window, though. i.e. all programs will (still) open on the same position.

Not an answer to you actual question, but: I stopped using dead keys long ago because I found it irritating to have to hit space whenever I needed to break out. Instead I mapped my CapsLock to be a Compose-key which lets me make almost any symbol I ever need in a very intuitive wsy. It works everywhere (incl. Wayland).