I'd like a function to make a window X% transparent (100% in my case) unless it is hovered over with the mouse, becomes the active (foreground) window, or for Y seconds (20 in my case) after the application makes a sound.

Bonus: Restrict the function to a specified process.
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Use-case for those interested:
I have 4 chat applications open at all times on my secondary monitor, and they are tiled in the four corners. This serves two purposes. 1: It allows me to see my desktop wallpaper until I choose to interact with one of the applications. 2: I can quickly spot which application made that "ding".

Ideally, I'd like to make four hotkeys for each of the four applications so I can toggle their transparency on/off independent of each other without needing to first select them. However, using the Win+Number keys they would become the active window and therefore become visible anyway so it's really only useful for applications in exclusive full-screen mode (such as games).

Thanks! ^_^