Its a small annoying part and not easily reproducible but it happens. Kubuntu 16.04 + backports ppa I am using empty panel with added widgets and not edited default one. I thought there is no difference between them but i was wrong see this bug https://bugs.kde.org/show_bug.cgi?id=361566 thats why i am letting you know. Reproducible: Sometimes Steps to Reproduce: 0. Enable panel auto-hiding 1. Press on something on a panel(launcher, menu, etc) 2. Put you mouse pointer away from a panel 3. Panel is not disappearing 4. Put you mouse pointer on a panel 5. Put you mouse pointer away from a panel 6. Panel auto-hides In 5 minutes of trying to reproduce it you may see it. The same problem was in KDE4 then at some point it was fixed, but in KDE5 it starts again.
I can confirm similar, but slightly different behavior. I am using focus-follows-mouse. That means that when a window pops up or disappears, the focus does not switch to the panel. If it has to be activated to remove or add a thumbnail, fine. Do that and then disappear again. It doesn't disappear until you give and remove focus. This is wrong. Even "wronger" is that sometimes it won't disappear even then. Once that happens, there is absolutely nothing you can do to make the panel go away. Except restart the desktop. That is a disruptive solution. So, once the panel refuses to go away, it cannot be gotten to go away without restarting the X desktop. The behavioral difference from this report is that there is no way to get it to auto hide after it fails once. *Additionally*, the panel's behavior under focus-follows-mouse is wrong.
Can confirm this behaviour
This is over 4 years old and no response from KDE devs. It's not as old as the request to restore wallpaper-per-desktop, but it leads me to think that KDE devs prefer to do what amuses themselves rather than address the needs of the users. Note to KDE devs: why don't you close as "won't fix because we don't feel like it" Yes, that is very snarky. I think after all these years, you've earned it.
No, we keep tickets for bugs open, even if we couldn't find a contributor to investigate and submit a patch.
I notice that you said "no response from KDE devs" two days after a KDE dev left a response. :) As you can see at https://bugs.kde.org/weekly-bug-summary.cgi, there are over 27,000 open bug reports. If you feel that this one isn't being prioritized properly, feel free to work on it yourself and submit a merge request that fixes the issue. I see from your impressive resume at https://savannah.gnu.org/people/resume.php?user_id=233 that you have exceptional technical abilities. We would welcome your assistance. If that's not your cup of tea, patience is appreciated. :)
I have a similar problem with plasma 5.19.5: Auto-hide panels raise themselves on all monitors on switching windows, by mouse or key, and remain raised until I click in the panel (on anything) then move the mouse cursor out of the panel. Only the panel clicked in hides. A *workaround* is to check settings, window management, window behaviour, advanced, special windows, hide utility windows for inactive applications. Then auto-hide works correctly, once each panel gets hidden. Note that there are no "special" or "utility" windows anywhere.
*** This bug has been marked as a duplicate of bug 351175 ***