Problem switching between external and internal monitor

[Boris Hollas]

Hello,

I have a docking station with an external monitor. When I take my laptop 
out of the docking station and open the lid, the internal screen is not 
activated and it remains off when I press fn+f7.

If I open the lid before taking the laptop out of the docking station 
and select the internal monitor with fn+f7, the internal monitor is 
activated but the internal mouse doesn't work.

I have similar problems when switching from or to beamer output.

I tried to fix these issues with the following script:

#!/bin/sh
LVDS=LVDS
VGA=VGA-0
DVI=DVI-0

xrandr | grep -q "$DVI connected" && DVI_ON=1 || DVI_ON=0
xrandr | grep -q "$VGA connected" && VGA_ON=1 || VGA_ON=0

if [ $DVI_ON -eq 1 ]; then
     xrandr --output $LVDS --off --output $DVI --mode 1920x1200
elif [ $VGA_ON -eq 1 ]; then
     xrandr --output $VGA --auto --output $LVDS --same-as $VGA
else
    xrandr --output $LVDS --mode 1680x1050
fi


but it doesn't work either. Screens remain blank when they shouldn't or 
the visible area is smaller than the apparent screen size, so I don't 
see the bottom panel. Sometimes, xrandr reports "cannot find crct".

This is the output of xrandr -q, laptop in docking station:

Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 8192 x 8192
DVI-0 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 
546mm x 352mm
    1920x1200      60.0*+
    1600x1200      60.0
    1680x1050      60.0
    1600x1000      60.0
    1280x1024      75.0
    1280x960       60.0
    1152x864       75.0
    1024x768       75.1     60.0
    832x624        74.6
    800x600        75.0     60.3
    640x480        75.0     60.0
    720x400        70.1
LVDS connected (normal left inverted right x axis y axis)
    1680x1050      60.1 +   50.1
    1400x1050      60.0
    1280x1024      59.9
    1440x900       59.9
    1280x960       59.9
    1280x854       59.9
    1280x800       59.8
    1280x720       59.9
    1152x768       59.8
    1024x768       59.9
    800x600        59.9
    848x480        59.7
    720x480        59.7
    640x480        59.4
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
VGA-0 disconnected (normal left inverted right x axis y axis)

Furthermore, my laptop has two GPUs so I can't use a static xorg.conf.

With Gnome 2, I was able to cycle between outputs using fn+f7. I use 
Xfce 4.8 on Debian Wheezy. Ideas?

-Boris