This might be a little complex. Maybe unsolvable IDK.
I have my HTPC connected to an 8K A/V receiver that connects to my display through eArc in 4K.
When I turn off my display, and it turns off the A/V receiver, the PC then swaps to 640x480...
For the most part this doesn't affect my windows/apps except for a few specific ones.
Unfortunately WACUP is one of those.
It sometimes moves the EQ and Playlist windows into the Main window.
But it always seems to widen the Playlist window.
I use the Triple Size option because 4K after all, and I have Windows' UI set to 200% so things look similar to how 1080p did.
So I figured I'd just have to enable Freeze Window Positions/States, except that doesn't seem to address any of the symptoms I'm experiencing. The Playlist still stretches, and the window positions still move sometimes.