Bug 163504

Summary:	Keyboard stops responding in Kwin, Ctrl + Alt shortcuts for X still work
Product:	[Plasma] kwin	Reporter:	Max Cantor <maxcantor>
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	cberger, mmtsales
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Max Cantor 2008-06-08 06:23:06 UTC

Version: (using Devel)
Installed from: Compiled sources

I'm on a Compaq Presario v2565us laptop; I installed the KDE 4.0 flavor of Kubuntu 8.04 and used a dist-upgrade on the "deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu hardy main" repo to get 4.1.

I'm using synergy (http://synergy2.sourceforge.net) with my Ubuntu laptop as a client to my Windows XP server, but I doubt that it's causing this issue. When it happens, I can still use the mouse plugged in to my Windows desktop to control the cursor on my Linux laptop.

The following things happen when this issue arises:

* No keys typed take effect, including Alt + Tab hotkeys
* Ctrl + Alt + F1 still switches to a terminal, and Ctrl + Alt + Backspace still restarts X
* Hitting Ctrl + Space has no effect (some Java frameworks apparently lock the keyboard when you hit Ctrl + Space)
* Hitting Fn + Alt + SysRq has no effect
* Right clicking has no effect
* Pidgin's menus (Conversation, Options, Send To) no longer expand when clicked. This may happen with other applications, but I didn't test it.

Possible causes or related problems, but don't take my word for it:
I recently built the Ruby programming language from source, and installed & uninstalled the "keytouch" packages while trying to get my volume keys to work. Also, I've noticed that tab completion doesn't work as expected on certain bash commands. For example, I used to be able to type "mpc search art<TAB>" to get "mpc search artist", but it doesn't work now.

I don't know how to reproduce it, and found no related information in /var/syslog or dmesg. It's happened twice in about 12 hours.

Restarting X with Ctrl + Alt + Backspace fixes the problem.

Comment 1 Marcelo Sales 2008-06-13 02:04:53 UTC

The very same thing has happened to me too, using Fedora 9, and it didn't happen until a few days before. However, every time this has happened here, the screensaver had been running for several minutes. I thought it was caused by the energy management configuration (which I have turned on recently), but I turned it off and the problem persists. Maybe it's related to the slideshow screensaver (which I also set up recently), but I still have to test this further. I've noticed that when this problem arises, kwin consumes more then 95% of the CPU until it's killed. To recover control over the GUI, I have to restart X using CTRL+ALT+BS.
Is the screensaver running when this problem happens at your machine?

Comment 2 Marcelo Sales 2008-06-16 04:19:34 UTC

It's seems that in my case it has something to do with the slideshow screensaver indeed. I selected another screensaver and have been almost 48 hours without seeing the kwin problem. Then I selected back slideshow and the problem is back again.
Using Fedora 9, KDE 4.0.5, nvidia FX 5500 with livna drivers and desktop effects on. Let me know if there's any test I can do to help trace the problem or if a should open a separate bug report for this.

Comment 3 Marcelo Sales 2008-06-19 22:39:26 UTC

More info: the problem (in my case) is indeed related to the slideshow screensaver. More specifically, it happens when the screensaver uses a specific transition effect, the one in which dots of the new image appear over the old one until the new image if fully shown. Everytime this transition effect is used, kwin stops responding and goes to 95% and up of processor utilization. However, it's still possible to change to a text terminal using CTRL+ALT+Fx or to restart X using CTRL+ALT+BS. Maybe there's a bug in the screensaver itself, but kwin certainly shouldn't freeze anyway.

Comment 4 lucas 2008-11-19 09:37:53 UTC

Does this still occur?

Comment 5 Cyrille Berger 2009-03-09 17:33:12 UTC

It still happens to me, sounds related to 155951. (and I don't have any screensaver, well just the blank one)

Comment 6 Thomas Lübking 2012-03-15 01:04:00 UTC

The original report sounds like a pointer or server grab, possibly dupe of bug #155951 or bug #171685 (notably since 163504 is between them ;-)

For this reason I doubt this is still an issue. If it is: SHOUT ;-)
(keyboard loosing is not funny)

The comments regarding the slideshow scrensaver derive from the massive complexity of the damage event it seems to cause.
The damage processing has been changed at least once since then to explicitly cover such "spam"

-> I'll tag this "works for me"
If there're still issues, please call back.