Could FocusIn/FocusOut mode be used?

[ypid]

I just stumbled over https://unix.stackexchange.com/questions/480052/how-do-i-detect-whether-my-terminal-has-focus-in-the-gui-from-a-shell-script

Sounds too good to be true. If this could be used, it would be one generic solution and no specific code for Tmux would be needed anymore (Edit: I might be wrong here. See the following comment). It could also solve Terminal emulators with multiple tabs and SSH. I am currently not motivated enough to test all this, mainly because on Qubes OS, the xprop -root _NET_ACTIVE_WINDOW does not work in VMs. When that is fixed/understood, I can return to this.

[Nanoseb]

That indeed looks pretty cool. Though, just did some quick tests and, as said in the comments of this answer, it doesn't seem to be working with tmux. But it works with ssh and probably tabs etc. that's already something.