This might be connected to the 'empty' frame assigned to Windows. Hover over the bottom-right taskbar button to show the 'empty' transparent windows (used to be glass placeholders in Windows 7) and it gives the same oddness as when you collapse a window. I don't know how that 'empty' frame is generated but it seems wrong.
Gyarados
I am trying to make a Curtains theme to satisfy my Windows 7 Aero Glass style needs, and I'm using modified Windows 8 RP assets to try do it. I feel like it's a good update to the classic Aero design (and using Windows 7 Aero assets don't work well in Curtains). This is never going to be perfect but here's how I currently have it looking. I'm not happy with it yet, blur in the title bars would help it feel right. <img src="https://i.imgur.com/6D64y9s.png" alt="" width="975" height="49
Windows 10 1909 Curtains 1.11 (also happens on 1.10), text shadows on titlebar shift the text by the blur amount. Using a fresh copy of Fluent Graphite to demonstrate. No other changes to Fluent Graphite were made. https://i.imgur.com/D5UY0Sv.mp4
I'm trying to make a theme with Curtains and I'm using "Replace Default Frames" and a transparent image for the titlebar. Could there be a setting to make it blur behind the titlebar, similar to the options for explorer content blur? This is what it looks like without blur.