Feature request: clear highlight definitions on `FocusLost`

[simonmandlik]

When I switch panes in tmux, the cursor disappears, but the highlights stay on. Would it be possible to clear the highlights on FocusGaines and possibly reenable when I switch back on FocusLost?

Thank you!

[giddie]

Actually it would be really nice to have a simple way even to toggle highlighting on and off manually 🤔