[Bug] hide_title_bar window effect causes visual glitch in PowerToys

[marzeq]

Describe the bug

With the hide_title_bar effect enabled, there is a white bar on top of the PowerToys window, see screenshot:

Reproduction

No response

Stack trace or error logs (if applicable)

No response

Version number

v3.4.0

[JonasWischeropp]

This is currently a problem with all windows, not only PowerToys. When you look closely, you can see that the terminal has a small bar at the top as well. It is just more noticeable when it is white, like in the case of PowerToys.

I wasn't able to remove this bar at the top without removing the borders around windows as well.
Windows (OS) for some reason leaves this bigger border at the top when removing the titlebar from a window.
This small bar at the top could be removed by removing the WS_THICKFRAME property from a window, but this would also fully hide the border around the window (the border that changes its color to indicates the currently selected window).
Setting WS_BORDER didn't change this behavior.

Just wanted to leave that here as an explanation why hide_title_bar behaves this way.
I currently don't have the time to look into it, but there might be ways to fix it. For instance, I stumbled across this StackOverflow question that might help.
Not a fix, but this problem could be made less obvious by setting the topbar color with DWMWA_CAPTION_COLOR.