Non-native apps are incorrectly mapped to the screen after changing text size

[cassidyjames]

It looks like somehow Gala loses track of non-native windows (i.e. Slack, an electron app) when changing the text size in System Settings → Desktop → Appearance. They're mapped incorrectly to the screen, i.e. the "real" window is somewhere other than it's drawn leading to mis-clicks and making them impossible to use.

I know we don't need to cater to non-native apps, but this really seems like something in Gala is broken, and I'm not sure it's something those apps are technically doing "wrong" by any means.