On Kwin_wayland in Plasma 5.7 beta, in the systemsetings window, the popup that appear when hovering a category is misplaced (it appears at the upper left corner of the screen instead of being below the icon) AND they open a "dummy" window in the Task manager. Reproducible: Always Steps to Reproduce: 1. Open System Settings 2. Put pointer on a category 3. Wait for the popup to appear ; it is misplaced Actual Results: The popup shows in the upper left corner of the screen Expected Results: The popup should be just under the category icon.
This is not a bug in KWin, but in QtWayland and/or systemsettings. It doesn't set proper transient information on the window. Thus KWin applies the normal window positioning.
OK ; should I open a bug report in the Systemsettings category ?
No, I'm quite certain it's a QtWayland issue. On X11 it looks like having proper transient information, so it's a Qt problem. For reporting against Qt I need to investigate more, though. Like checking the code and creating an example.
Just for information, this is not fixed in Plasma 5.8 beta.