Corrupt title/header bar, no window decorations on small pop-up windows

[VanessaE]

I am using gtk3-nocsd version "3-1" from Debian's standard bullseye repository.

I don't know what the proper name is for these pop-up windows, but I refer to the small ones some programs use which generally ask a simple question, like "are you sure you want to quit?" or "overwrite this-such-and-such file?", and similar. The phrase "nonmodal" comes to mind in reference to this type of popup, not sure if that's correct.

Anyway, these kinds of windows are being given corrupt title bars and no window decorations. For example, here's Prusaslicer exporting to g-code and ready to overwrite an old file:

Here, you can see the Prusaslicer main window in the background, a normal kind of window that doesn't use CSD, and which is not focused (hence light grey window decorations), a file dialog window that uses CSD but is being correctly altered by gtk3-nocsd, and has focus (thus the purple window decor), and a confirmation popup on top of that which clearly uses CSD as well, but which showing a broken top portion and no window decor.

What you can't see in the image is that that broken area is rapidly flickering between a few distinct states, including some transparent bits, almost like it's trying to interlace two images, or animate something (neither of which is actually appropriate for the window decorations I'm using).

Incidentally, this is a very handy utility. The more of this CSD crap that shows up, the worse the desktop looks, imho. That is, until gtk3-nocsd came about. Thanks for restoring some sanity to my desktop. :smile"