This is not fully accurate as a summary because the issue is pertty complex to describe but you get the mood: I've been experiencing this bug since the beginning in Xfce 4.10. As always I set the focus to follow the mouse pointer and have windows raise to the foreground one-two seconds after they've received the focus.
That particular setting causes dockable windows of applications set in full screen mode (e.g. in Gimp but also MyPaint) to disappear in the foreground when clicked, while they should stay. Also, I noticed, again with the same settings and full screen windows: set Gimp in multi-window mode, hover a dockable tool, the latter is sent to the background... then reappears shortly after... then disappears again...
This phenomenon loops until the mouse clicks the window (sending it behind the main window for good) or leaves the dockable window. BUT the phenomenon does not occur the first time I hover a docakble window. I need to hover the dockable window, return to the main Gimp window and hover the dockable window again and only then the flapping occurs.
The issue can be always reproduced.
Summary of the conditions:
- Focus follows mouse AND
- Auto raise focused windows (delay doesn't matter) AND
- Application runs full screen AND
- +-- has dockable windows (MyPaint, Gimp) AND
- Hover a dockable window, twice
then hovering a dockable window makes it flap, faster with a short focus delay, slower with a longer focus delay, regardless of the raise delay.
It's not over!
If auto focus is not set (but "Auto raise when focused" is set), clicking on a dockable window makes all the other dockable windows disappear behind the full screen application... until I click the main application again. Or switch back and forth with Alt+Tab.
Hope this helps.