Bug 184785

Summary:	Keyboard stops working after using [alt]-[tab] quickly
Product:	[I don't know] kde	Reporter:	Vidar L <vl>
Component:	general	Assignee:	Unassigned bugs mailing-list <unassigned-bugs>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	kde4, kde, marek.trylinski, mihai.dontu, stormlabs
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	unspecified
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Vidar L 2009-02-18 14:28:09 UTC

Version:            (using KDE 4.2.0)
OS:                Linux
Installed from:    Unlisted Binary Package

Hi

Sometimes, when using [alt]-[tab] (in order to switch between programs) the keyboard stops working afterwards. That is, it doesn't work in any programs. I can use mouse to for instance cut&paste text but there is no way I can type in new text using the keyboard. 

I think this happens (or has a bigger chance for happening) when I use [alt]-[tab] combination too quickly. For instance releasing the keys again  even before the task list has been displayed on screen. It might also easier happen if I close a window (click the X in kwin's border) and then press [alt]-[tab] before window has yet managed to be closed (The window will then be closed while the application list is displayed).


Frequency of this bug? :
I updated from KDE4.1.4 to KDE4.2.0 yesterday and it has now happend 3 times after I upgraded (did not experinece this in KDE4.1.4)

I have disabled desktop effects (so I don't use box switch, cover switch or anything like that)

The only way I have figured out to make my keyboard work again when this happens is to logout (by using the mouse).
The keyword then works again when I am prompted for login by kdm

I am using Kubuntu with the KDE4.2.0 packages available from their Kubuntu Experimental Software Personal Package Archive (PPA) repository

Comment 1 Tony O'Bryan 2009-02-18 15:53:27 UTC

*** Bug 184797 has been marked as a duplicate of this bug. ***

Comment 2 Mihai DONȚU 2009-04-15 20:49:30 UTC

The same thing happened to me (kde 4.2.2). I was writing something in kate, I switched to konsole, ran a command there, switched back and tried to correct something in kate but the keyboard was not working anymore. I don't know why. It happened twice this week. I have a friend with OpenSuse who is having the same problem (I think a little more frequent than me). None of us uses any desktop effects or anything dubious.
I used to have kde 3.5.8 but I removed it and renamed ~/.kde3.5 to ~/.kde3.5-old (otherwise kde4 would not start).
The solution, so far, was to log out and then log back in.

Comment 3 Ricardo Ferreira 2009-05-01 01:34:05 UTC

This happened to me a few times now. Its really annoying. Until i read this bugreport i didnt really understand why it happened! All i know is all of a sudden i loose my keyboard and everytime i move the mouse while i left click, it moves the window so it appears the ALT key is stuck.

This is a serious bug. It can cause you to loose all your unsaved work.

Comment 4 Marek Tryliński 2009-05-08 02:49:31 UTC

i can confirm it too, it also happens when combining Alt+Tab with Alt+1,2,3 etc (changing desktop)

i have 4.2.2

Comment 5 Vidar L 2009-05-08 09:22:46 UTC

I have now updated to newest kubuntu / ubuntu v9.04 and still have the problem.

However, in most cases  Tony O'Bryan workaround suggested in 184797 works fine:
If you open the "Configure Window Behavior" KDE control module the keyboard works again.
(I don't even have to "enable (or disable) 3D effects to restore keyboard processing." as Tony says. In most cases it works just by open the "Configure Window Behavior" window and close it again).

In some cases ( I think I have experienced it two times now), this workaround doesn't work either. Then a logout and login is only way to make the keyboard working again AFAIK .

Comment 6 Michael Jansen 2009-05-21 16:40:21 UTC


*** This bug has been marked as a duplicate of bug 171685 ***

Comment 7 Mihai DONȚU 2010-06-22 03:43:03 UTC

I am revisiting some of the bugs I've been involved before. This one seems to be fixed (it's been a very long time since I stumbled into it). Pity nobody seems to have an explanation for it.

Comment 8 Mihai DONȚU 2010-06-22 03:44:44 UTC

Never mind, I just read #171685.