Bug 316195

Summary:	Auto-hidden panel is unable to unhide at some point
Product:	[Unmaintained] plasma4	Reporter:	mkkot <marcinkocur>
Component:	panel	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	michal.seweryniak, nate, xypron.glpk
Priority:	NOR
Version First Reported In:	4.10.1
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description mkkot 2013-03-05 22:18:54 UTC

I don't really know what the conditions are to reproduce this bug, but I think it's verry common. I have a panel at the bottom of the desktop which should hide automatically (as I set it to do so). And it hides as it should. When I move the cursor next to the bottom edge of the screen, the panel shows up again, and that's also fine. However, try to work with this autohide setting for a half hour and I'm sure at some point you will be unable to bring this panel back visible.

Reproducible: Always

Steps to Reproduce:
1. Set up plasma to have one panel at the bottom of the screen with menu launcher, virtual desktops applet, task manager, tray and a clock (it's a very standard setup if not a default one)
2. Set panel to autohide
3. Do your daily work
Actual Results:  
At some point the panel won't show up when you move your cursor agains the bottom of the screen

Expected Results:  
Panel shows up instantly every time you move your cursor agains the bottom of the screen

Comment 1 Michał 2013-03-22 23:30:46 UTC

I have the same bug here - since yesterday, after upgrading my OpenSuse to 12.3 (KDE 4.10.1).

I think I found the way to reproduce the bug (it works for me every time): 
after setting the bottom panel to autohide (steps 1&2 from the previous post), run any application, that can open a dialog window, i.e. run Dolphin and open its configuration settings window (new child window). Now move the cursor to the bottom, where the panel is supposed to show up. Nothing happens.
To bring the autohidden panel back, you can switch to other opened window using Alt-Tab or just open start menu using Alt-F1. I've discovered, that Alt-F2 does the job too.
This is repeatable for every application that opens a dialog child window.

Comment 2 Heinrich Schuchardt 2017-08-22 16:26:53 UTC

I have identified one situation that reproducably leads to the behavior:

When thunderbird is opened it displays a dialogue to ask for the email
account password.

While this popup is shown in thunderbird the panel does not autohide
when changing to another application.

Best regards

Heinrich Schuchardt

Comment 3 Nate Graham 2018-01-23 20:25:11 UTC

Unfortunately, this is caused by a flaw in the way X11 is designed, compounded (apparently) by something that Thunderbird's doing. windows are allowed to block input for others. The auto-hide panel is implemented with an invisible 1-px window on the edge where the panel hides. This window needs input, but apparently Thunderbird is blocking it.

You can file a bug against Thunderbird, or use Plasma 5 with Wayland, which doesn't have this architectural limitation.