Visual cue on window focus

[henrythor]

I use wezterm with window_decorations = "RESIZE" which is good and what I want basically. Minimum clutter on my desktop. But a side effect is that I don't get a good visual cue when I switch windows so it takes me a few milliseconds to locate the cursor on my window to see if it's focused.

My use case is that I use Aerospace window manager on MacOS and am switching between windows with keyboard gestures much like i3 in Linuxland.

Is there something I could do in Lua for this, could I check if the current window is focused in on window-focus-changed and if so could I invert the theme and launch a timer that changes it back in like 0.2 (or less) seconds?

Preferably I'd like some sort of border to flash or something but an invert would be fine too.