Bug 203558

*** Bug 206370 has been marked as a duplicate of this bug. ***

*** Bug 206374 has been marked as a duplicate of this bug. ***

*** Bug 206162 has been marked as a duplicate of this bug. ***

This bug is extremely hard to reproduce and I believe that the root cause might be the same as of the bug #202199. Many conditions must be met (size, timing and race condition) in order for plasma-desktop to crash. However, a developer who knows the code well might understand what's going on. What is more, I believe it is nearly impossible to reproduce this with plasmoidviewer, only with plasma-desktop.

So I have a panel at the bottom of the screen with the following widgets from left to right: kickoff, show desktop, devices recently plugged in, desktop pager (4 desktops, 2 rows), tasks, systray and digital clock. I have 8 icons in the systray, one is hidden. Plasma is unlocked. I have 3 apps visible in the taskbar (akregator, konqueror and konversation). Now I open kickoff menu, select konqueror and... plasma-desktop crashes emitting the following error:

QGraphicsScene::removeItem: item 0x2197880's scene (0x0) is different from this scene (0x86bd80)
KCrash: Application 'plasma-desktop' crashing...                                                

Now my speculation what is going on here. When I select konqueror from kickoff menu, "Loading konqueror" task appears in the taskbar. At the same time, something (?) triggers resize of the panel and for *a very short time* (sometimes even invisible to an eye) the taskbar splits into two rows (during resizing). I don't know how it is technically done then but I guess another QGraphicsScene is created for another row (pure speculation) and "Loading konq" task is added to it. When resizing is done, taskbar goes back to single row mode (maybe it detects that two rows don't fit?), however konqueror finishes starting and obviously "Loading konq" task needs to be removed. However, with taskbar in a single row mode, it tries to remove "Loading konqueror" from the 2nd (non-existing?) row. So plasma-desktop crashes...

The big variable here is why micro-resize of the panel is triggered. It confuses taskbar widget which attempts to layout items in two rows and changes mind in a few hundreds of miliseconds. That combined with (unfortunate) need to remove "Loading konqueror" task eventually leads to plasma-desktop crash.

I really hope this information helps to solve (both) the(se) bug(s). They really drive me nuts.

Contents of my plasma-desktop-appletrc can be found below (with privacy sensitive info removed):

[$Version]
update_info=plasma_popupapplet_fix_groups.upd:PlasmaPopupAppletFixGroups1

[AppletGlobals][plasma_applet_systemtray]
ShowApplicationStatus=true
ShowCommunications=true
ShowHardware=true
ShowJobs=true
ShowNotifications=true
ShowSystemServices=true

[Containments][24]
activity=Desktop
desktop=-1
formfactor=0
geometry=0,0,1280,1024
immutability=1
location=0
plugin=desktop
screen=0
wallpaperplugin=marble
wallpaperpluginmode=
zvalue=0

[Containments][24][Applets][27]
activity=
desktop=-1
formfactor=0
geometry=0,15.0000000000001,883,754
immutability=1
location=0
plugin=
screen=-1
zvalue=963

[Containments][24][Applets][27][Configuration]
activity=
desktop=-1
filter=0
filterFiles=*
formfactor=0
geometry=0,15.0000000000001,883,754
immutability=1
location=0
mimeFilter=
plugin=folderview
screen=-1
url=desktop:/
zvalue=209

[Containments][24][Applets][28]
geometry=862,32,418,357.000000000001
immutability=1
plugin=plasma_applet_notes
zvalue=670

[Containments][24][Applets][28][Configuration]
autoFontPercent=3
scrollValue=0

[Containments][24][Applets][30]
geometry=883,684,400,300
immutability=1
plugin=
zvalue=968

[Containments][24][Applets][30][Configuration]
pressureFormat=7
tempFormat=1
updateWeather=30
visibilityFormat=16
windFormat=4

[Containments][24][Applets][30][Configuration][Vilnius]
ion=bbcukmet

[Containments][24][Applets][31]
geometry=16,774,200,200
immutability=1
plugin=pastebin
zvalue=813

[Containments][24][Applets][31][Configuration]
HistorySize=3
ImageBackend=0
TextBackend=1
imagebinca=http://imagebin.ca
imageshack=http://imageshack.us
pastebinca=http://pastebin.ca
pastebincom=http://pastebin.com

[Containments][24][Applets][36]
geometry=901,524.999999999998,370,440
immutability=1
plugin=news
zvalue=797

[Containments][24][Applets][36][Configuration]
interval=30
showDescriptions=false
showTimestamps=true
showTitles=true

[Containments][24][ToolBox]
corner=1
offset=0

[Containments][24][Wallpaper][image]
slideTimer=600
slidepaths=/usr/share/wallpapers/
userswallpapers=
wallpapercolor=56,111,150
wallpaperposition=0

[Containments][24][Wallpaper][marble]
mapTheme=earth/bluemarble/bluemarble.dgml
movement=0
positionLatitude=46.2764137640567
positionLongitude=30.1837535369751
projection=0
quality=1
rotateLatitude=0
rotateLongitude=0.025
rotationTimeout=120000
showPlacemarks=false
zoom=1241

[Containments][24][Wallpaper][weather]
updateWeather=30
userswallpapers=
wallpapercolor=56,111,150
wallpaperposition=0

[Containments][3]
activity=
desktop=-1
formfactor=2
geometry=0,-41,1206,35
immutability=1
location=4
plugin=panel
screen=0
zvalue=150

[Containments][3][Applets][16]
geometry=4,3,32,32
immutability=1
plugin=launcher
zvalue=0

[Containments][3][Applets][23]
geometry=814,3,266,32
immutability=1
plugin=systemtray
zvalue=484

[Containments][3][Applets][23][Configuration]
AutoHidePopup=true
hidden=

[Containments][3][Applets][23][Configuration][ExtenderItems][1]
extenderIconName=
extenderItemName=jobGroup
extenderItemPosition=0
extenderTitle=
groupCollapsed=false
isCollapsed=false
isGroup=true
sourceAppletId=23
sourceAppletPluginName=systemtray

[Containments][3][Applets][23][Configuration][ExtenderItems][119]
labelName0=Šaltinis
labelName1=Tikslas

[Containments][3][Applets][23][Configuration][ExtenderItems][121]
label1=
labelName0=Šaltinis
labelName1=

[Containments][3][Applets][23][Configuration][ExtenderItems][123]
labelName0=Šaltinis
labelName1=Tikslas

[Containments][3][Applets][23][Configuration][ExtenderItems][2]
extenderIconName=
extenderItemName=completedJobsGroup
extenderItemPosition=0
extenderTitle=0 neseniai baigtų užduočių:
groupCollapsed=false
isCollapsed=false
isGroup=true
sourceAppletId=23
sourceAppletPluginName=systemtray

[Containments][3][Applets][23][Configuration][PopupApplet]
DialogHeight=75
DialogWidth=200

[Containments][3][Applets][23][PopupApplet]
DialogHeight=14
DialogWidth=0

[Containments][3][Applets][34]
geometry=1084,3,96,32
immutability=1
plugin=digital-clock
zvalue=0

[Containments][3][Applets][34][Configuration]
announceInterval=0
defaultTimezone=Local
displayHolidays=false
holidaysRegion=lt
plainClockColor=255,255,255
plainClockFont=Liberation Sans,20,-1,5,50,0,0,0,0,0
showDate=true
showDay=true
showSeconds=true
showTimezone=false
showYear=false
timeZones=
useCustomColor=false

[Containments][3][Applets][34][Configuration][ExtenderItems][6]
extenderIconName=view-pim-calendar
extenderItemName=calendar
extenderItemPosition=0
extenderTitle=Kalendorius
isCollapsed=false
sourceAppletId=34
sourceAppletPluginName=digital-clock

[Containments][3][Applets][34][PopupApplet]
DialogHeight=270
DialogWidth=246

[Containments][3][Applets][37]
geometry=40,3,32,32
immutability=1
plugin=showdesktop
zvalue=729

[Containments][3][Applets][37][Shortcuts]
global=Meta+D

[Containments][3][Applets][5]
geometry=76,3,32,32
immutability=1
plugin=notifier
zvalue=0

[Containments][3][Applets][6]
geometry=112,3,41,32
immutability=1
plugin=pager
zvalue=0

[Containments][3][Applets][7]
geometry=157,3,653,32
immutability=1
plugin=tasks
zvalue=815

[Containments][3][Applets][7][Configuration]
showOnlyCurrentDesktop=true
showOnlyCurrentScreen=true

[Containments][3][Configuration]
maximumSize=1241,35
minimumSize=1206,35

[General]
immutability=1

*** This bug has been marked as a duplicate of bug 199615 ***

@Beat: are you sure those reports are the same ? The second one seems more related to some Python widget/scriptengine while this is related to the taskbar.

*** Bug 210082 has been marked as a duplicate of this bug. ***

@dario, good question. i actually think it's a bug in qt, just triggered from two different paths. But we can reopen it if you disagree. it's indeed hard to tell.

Ok, reopening... Thanks

this is the preferredSize crash ... forget what the # is. already submitted a fix for it.

*** Bug 211564 has been marked as a duplicate of this bug. ***

*** Bug 211674 has been marked as a duplicate of this bug. ***

*** Bug 212094 has been marked as a duplicate of this bug. ***

*** Bug 214937 has been marked as a duplicate of this bug. ***

*** Bug 215886 has been marked as a duplicate of this bug. ***

*** Bug 216607 has been marked as a duplicate of this bug. ***

*** Bug 217934 has been marked as a duplicate of this bug. ***

*** Bug 217912 has been marked as a duplicate of this bug. ***

*** Bug 218239 has been marked as a duplicate of this bug. ***

*** Bug 218325 has been marked as a duplicate of this bug. ***

If so many people are still reporting this issue with the latest code (see the 10 duplicate bug reports in the last two months), why is this issue set to "RESOLVED as FIXED"?  I certainly am still seeing plasma desktop crashing on a fairly regular basis, and obviously I'm not the only one.

AFAIK, this is fixed in KDE SC 4.4, and may be in the last 4.3 version (4.3.4) too.
All the reports marked as duplicates are using 4.3.2 or 4.3.1 (not the "latest code")
There are other taskbar related crashes which are being tracked in different bug reports too..

*** Bug 218490 has been marked as a duplicate of this bug. ***

*** Bug 219120 has been marked as a duplicate of this bug. ***

*** Bug 222220 has been marked as a duplicate of this bug. ***

*** Bug 222856 has been marked as a duplicate of this bug. ***

*** Bug 223056 has been marked as a duplicate of this bug. ***

*** Bug 223205 has been marked as a duplicate of this bug. ***

*** Bug 225392 has been marked as a duplicate of this bug. ***

*** Bug 227446 has been marked as a duplicate of this bug. ***

*** Bug 228330 has been marked as a duplicate of this bug. ***

*** Bug 224433 has been marked as a duplicate of this bug. ***

*** Bug 229080 has been marked as a duplicate of this bug. ***