On a notebook, in the "kcmshell4 display" - dialog it is possible to create a multihead configuration that blackens the notebook screen. This is not wrong as long as you have external screens activated. But if you save such a configuration as standard and unplug the external monitors, you still get a black screen on the notebook and can't see anything at all. 

This is not nice for user who put their notebook in a docking station to use two external monitors.

Our system is based on Ubuntu 12.04, but modified.


Reproducible: Always

Steps to Reproduce:
Tested on a notebook, in this case a lenovo X220i
1. Connect external vga-monitor to the notebook.
2. Open kcmshell4 display
3. Configure screens so that the notebook screen is deactivated and the vga screen is active.
4. Save as standard configuration.
5. Switch off the notebook.
6. Unplug vga monitor.
7. Switch on notebook.
8. Kdm starts, login 

Actual Results:  
Kdm crashes, screen remains black, no way to get out for a normal user. Workaround is deleting ~/.kde4/share/config/krandrrc and restart Kdm.

Expected Results:  
A sensible default monitor configuration is chosen, with the notebook screen enabled.

I have noticed that the multihead configuration is set in /usr/bin/krandrstartup. This script does not check the return value of xrandr, which could imho solve the problem. If xrandr returns an error, a sensible default configuration should be activated.
I will provide a patch, you can use it if you like it.