Adding a second monitor to my desktop via xrandr --output VGA --right-of LVDS --auto worked ok (except the desktop background, but thats a different bug). After creating a new konqueror window on the second screen and opening bko in it kwin crashed and at the same time the plasma panel moved from its bottom location on the first screen to the top of the first screen. The panel was fine after adding another screen, it only happened once I interacted with the konqueror window on the second screen and kwin crashed.
Just retried and its perfectly reproducable: Grab a window title, move the window into the second screen. This crashes kwin and it also makes the panel vanish. Not the desktop background though, so I assume not all of plasma is crashing at that point. When the panel and kwin come back, the panel is at the top of the first screen.
And another note: Due to 179607 I can't really move the panel myself back to the bottom, but it seems when playing around with the size handles a bit it jumps back to the bottom itself. I also just noticed (trying to move it back to the top via this bugreports steps) that it doesn't necessarily happen the first time kwin crashes. Might need a second try of moving the window on the second screen to move the panel...
Captured plasma kdebug output while moving a window from screen 0 to screen 1 and the panel jumped to the top: plasma(21082) PanelView::updateStruts: screen l/r/b/t offsets are: 0 1680 150 0 4 plasma(21082) TaskManager::AbstractGroupingStrategy::createGroup: Object::connect: Attempt to bind non-signal TaskManager::TaskGroup::editRequest() plasma(21082) TaskGroupItem::reload: plasma(21082) TaskGroupItem::isActive: Not Implemented
*** Bug 179607 has been marked as a duplicate of this bug. ***
i doubt this has anything to do with plasma. the panel asks to move to a certain location on screen, but it's the window manager that actually allows it to do so. that it repositions properly as soon as you alter the settings says that plasma internally has the right bookkeeping, but that the window manager has moved the window elsewhere "behind its back". let's get the window manager crash fixed, and then when that's done, revisit this bug. i trust you've filed a report with kwin with a backtrace? can you reference the bug # in a comment in this report, please? thanks.
There's only one xrandr kwin bugreport: https://bugs.kde.org/show_bug.cgi?id=173017
Ok, seems like the real issue for both plasma and kwin has been kephal. Luckily I've got help from one of the kephal devs and he was able to fix the problems I've seen (there's one remaining which happens with cloning/"un-cloning" screens ). So I'm closing this as duplicate of the xrandr bug in kwin. Commit is pending, along with backporting to 4.2 and closing the bugreport. *** This bug has been marked as a duplicate of bug 173017 ***