Everything KDE from compiled from git master on top of Fedora 34. STEPS TO REPRODUCE 1. Open a YouTube video in one tab in Firefox 2. Open another website in another tab 3. Pop the YouTube video out into its PIP window 4. Switch to another tab OBSERVED RESULT The PIP window goes behind Firefox's main window. To make it appear on top of all other windows, I have to right-click in the window and go to More Actions > Keep Above Others. EXPECTED RESULT The window floats on top of all other windows automatically, as it does on X11.
bug report in mozilla bug tracker: https://bugzilla.mozilla.org/show_bug.cgi?id=1621261 Apparently a new Wayland protocol is necessary.
Ugh. In the meantime, maybe we could ship a window rule for this...
*** This bug has been marked as a duplicate of bug 422153 ***