Version: (using KDE 4.2.0) Compiler: GCC 4.1.2 OS: Linux Installed from: Gentoo Packages Using a dual monitor setup on KDE 4.2 with a nVidia GeForce GO card, the right hand monitor will flicker momentarily in strips whenever a notification, menu, dialog, etc appears. Even when a menu (or etc) pops up on the left monitor, the right monitor flickers for a bit while the widget is being drawn. This also occurs when using any of the desktop effects that take over the screen -- cube, zoom out, scale and cover selection, etc. I've eliminated hardware problems as the cause -- If I change my Xorg to swap the left and right monitors, the flicker changes to always appear on the right monitor. The flicker looks like the screen is being torn -- there are jagged, parallel, diagonal lines across the screen with black in between them. Disabling compositing makes the problem go away. I recall (years ago) that beryl would do this too, but then one day it just stopped after an update. So there is SOME way to fix it, I just wish I knew when that fix occurred so I could track it down. :)
Created attachment 31271 [details] My xorg Let me know if there are any other logs/configs/etc you'd like to see.
What happens when you deactivate "Use VSync" in System Settings -> Desktop -> Advanced?
The problem persists with VSync is disabled. I just tried changing the other settings in the dialog, but the only one that "fixed" it was switching to the XRender engine, which is horribly slow.
I can confirm flicker problems here when using kwin with compositing enabled. It appears on both screens here. When using a single screen xorg.conf with twinview disabled the problem disappears (1280x1024 depth 24). When using a single screen xorg.conf with twinview disabled but with Virtual 1920 1024 in SubSection "display" the problem appears again (!) When switching to Xfwm 4.6.0 ( xfwm4 --replace & ) with compositor enabled via xfce4-settings-manager the problem disappears. When killing plasma ( kquitapp plasme ) the problem disappears too. Steps to repoduce this with high chances: - set up xorg.conf with nvidia driver and some wide virtual screen resolution or twinview. - enable kwin desktop effects using OpenGL - open about ten lange application windows - klick on some application menu to pull it down - move mouse back and forth across the menu bar to switch between pull down menus frequently - if no problem occours, activate some other window, and try again ArchLinux 686 kdebase-workspace 4.2.1-2 qt 4.4.3-5 xorg-server 1.5.3-4 nvidia 180.29-3
Created attachment 31884 [details] xorg.log
Just in case: mesa 7.2-1
(In reply to comment #4) > When killing plasma ( kquitapp plasme ) the problem disappears too. Hmm, in a Xfce4 session when using kwin instead of xfmw4 it happens too. So plasma can't be the reason for this.
Created attachment 31905 [details] Messages from kwin
Ups !? Now i clicked on button Defaults in systemsettings section Display and restored all settings manually as before and the problem seems gone.
Restored the previous kwinrc from backup to track it down further. Result: With pull down menus it happens only when effect Scale In is enabled. Weird, since this effect does not affect menus anyway.
If this problem is the same as the one I experience (Flickering on both screens) it usually fixes itself if you change a setting. To have it reoccur you must restart KWin from the terminal with `kwin --replace &`.
(In reply to comment #11) `kwin --replace &` makes no difference here, but with 'Scale In' disabled it still seems to happen rarely with tooltips and sometimes with menus when clicked first time after unminimizing a window.
could this be a duplicate of bug #177495?
@ Comment #13: I don't think that this is a duplicate. The flickering described here is related to dualscreen setting (twinview) rather than to a window being maximized. I can confirm the flickering here. I have a dual screen setup. Left screen: external monitor @1680x1050, right screen is internal notebook screen @1280x800. Twinview setting @2960x1050. All settings done as root via nvidia-settings gui tool. I have had no previous Xorg.conf and created one from scratch using the NVIDIA settings tool. The flickering appears on the right (notebook) screen only. It flickers if I use desktop effects such as woggly windows ("wabernde Fenster"). The flickering also appears during the initial display of the desktop after booting the notebook. I have played with the vsync settings etc. and have noticed that sometimes I get less flickering or even none, but it reappears. It does not happen with all effects but with some. Compositing is enabled as is GLX. I have to use the binary NVIDIA driver (latest version). My graphic card is an onboard NVIDIA GeForce 6100 card. The flickering: It looks like a black area with horizontal lines blended into/over the desktop background, like a shadowing effect. It covers about half of the notebook screen. HTH.
I've been experiencing the exact same flickering issues as you. Twinview on geforce go 6150, xorg 1.9 , nvidia-drivers 256.53. Disabling "Allow Flipping" under X Screen 0 > OpenGL Settings within the nvidia-settings application fixed the issue for me.
I can confirm that setting "AllowFlipping" to "false" in the xorg.conf file solves flickering issue. Now desktop effects work without flickering.
given comments #15 and #16 this is not a kwin issue, but either a configuration issue or a driver issue. Most likely driver.
just for records: sounds like the nvidia drivers don't like flipping (the flicker is apprently related to glXSwapBuffers) with a multiscreen setup. if we've only swapping with GLES and later on maybe all GL, kwin should implicitly disable flipping (runtime driver parameter) on multiscreen detection.