Version:           unspecified (using KDE 4.6.0) 
OS:                Linux

I have my notebook with an external monitor attachted. My notebook has a display resolution of 1280x800 and my monitor 1920x1200. I am using the NVIDIA driver 260.19.36. I have my taskbar at the bottom of the screen width is full monitor width. When attached the external monitor is my primary one. So if on my notebook the taskbar is 1280px width, when on external monitor its 1920px wide.

When I shut down my computer with external monitor active and then reboot and login my notebook display is used only and the taskbar is as it should 1280 pixels wide. But when I reactivate my external Monitor it does not restore the full width of the 1920 pixels. It's still 1280 pixels wide. I have to rescale the taskbar everytime.

But when I turn of my external monitor and switch back to my notebook monitor as the primary one it works as expected. If I reboot and activate my monitor it restores the full width.

The problem only appears when shutting down the computer with external monitor active.

I took a look at the plasma-desktoprc file and I see the following for my 1920px resolution:

[PlasmaViews][3][Sizes][Horizontal1920]
max=-1,-1
min=-1,-1
offset=0

When I turn the external monitor of before shutting down the entry is correct with:

[PlasmaViews][3][Sizes][Horizontal1920]
max=1920,38
min=1920,38
offset=0

So it seems the there is a problem getting the correct horizontal value when the external monitor is activated while shutting down.

I hope this is in some way understandable as it is not that simple to explain :)

Reproducible: Always

Steps to Reproduce:
Notebook with external monitor attached, different resolutions.

1) External monitor is primary, displaying taskbar with full width
2) Shut down computer and reboot
3) Login and reactivate external monitor

Actual Results:  
Taskbar does not use the full width, just the width of the internal monitor.

Expected Results:  
Taskbar should expand to the full size.