I have a laptop with built-in 1366x768 resolution screen and an external monitor with 1280x1024 resolution (it is set as a primary display). A main panel (the one with task manager and application manager) is placed vertically at the right side of external monitor. Each time I plug the external monitor out, main panel changes its position and moves to laptop screen (it is OK). What is not OK is that it shifts down and is partially out of laptop screen boundaries. If I plug monitor in again, things become even worse. Popup widgets (I don't really know how to properly name them, I mean ones that appear on clicking tray icons, for example, network manager or volume control) are displayed at the top edge of the another monitor, KRunner widget is placed at a wrong position too (and actually is invisible at all). After i log out and log in again everything works fine both with a single- and a multi-monitor configuration.

Reproducible: Always

Steps to Reproduce:
1. Log in with an primary external monitor connected
2. Disconnect the external monitor
3. See panel shifted
4. Connect the monitor again
5. See widgets displaced

Actual Results:  
Main panel shifted (see screenshot — http://imgur.com/ONksD80), popup widgets are displayed on the wrong screen after clicking on a task icon (see screenshot — http://imgur.com/gZuWXue), KRunner is not displayed at all (probably displayed outside screen boundaries)

Expected Results:  
None of the above; widgets are in correct positions and usable

Here is an output of xrandr -q command with external monitor connected:

Screen 0: minimum 8 x 8, current 2646 x 1024, maximum 32767 x 32767
LVDS1 connected 1366x768+0+256 (normal left inverted right x axis y axis) 344mm x 193mm
   1366x768      60.06*+
   1360x768      59.80    59.96  
   1280x720      60.00  
   1024x768      60.00  
   1024x576      60.00  
   960x540       60.00  
   800x600       60.32    56.25  
   864x486       60.00  
   640x480       59.94  
   720x405       60.00  
   680x384       60.00  
   640x360       60.00  
DP1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
VGA1 connected primary 1280x1024+1366+0 (normal left inverted right x axis y axis) 334mm x 270mm
   1280x1024     60.02 +  75.02*
   1024x768      75.08    75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    60.00  
   720x400       70.08  
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

and here is an output without second monitor (when widgets are broken already):

Screen 0: minimum 8 x 8, current 1366 x 768, maximum 32767 x 32767
LVDS1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1366x768      60.06*+
   1360x768      59.80    59.96  
   1280x720      60.00  
   1024x768      60.00  
   1024x576      60.00  
   960x540       60.00  
   800x600       60.32    56.25  
   864x486       60.00  
   640x480       59.94  
   720x405       60.00  
   680x384       60.00  
   640x360       60.00  
DP1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)