xrandr and external touchscreen on notebook

[Wolfgang Rohdewald]

Hi,

I can make the external touchscreen work with this:

xrandr --output LVDS1 --right-of DVI1
which gives me 1920x1080 on DVI1 and 1920x1200 on the notebook.

Now the touchscreen moves the mouse relative to the entire 
virtual screen (3840x1200). How can I restrict the touchscreen
inputdevice to the external monitor?

I believe it should work with xorg.conf (see below) entry but it
seems that xrandr ignores this.

I am running kubuntu 9.10 with backported KDE 4.4
X.Org X Server 1.6.4

root at notebook:/etc/X11# cat xorg.conf

Section "ServerFlags"
        Option  "DontZap"       "True"
EndSection

Section "InputDevice"
        Identifier "Acer T230H"
        Driver "evdev"
        Option "Device" "/dev/input/by-id/usb-Acer_T230H-event-if00"
        Option "Calibration" "0 1920 0 1080"
EndSection

Section "ServerLayout"
        Identifier "Touchscreen"
        InputDevice "Acer T230H" "SendCoreEvents"
EndSection

notebook:~$ xrandr -q
Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 4096 x 4096
VGA1 disconnected (normal left inverted right x axis y axis)
LVDS1 connected 1920x1200+1920+0 (normal left inverted right x axis y 
axis) 367mm x 230mm
   1920x1200      60.0*+
   1600x1200      60.0
   1680x1050      60.0
   1600x1024      60.2
   1400x1050      60.0
   1280x1024      60.0
   1440x900       59.9
   1280x960       60.0
   1360x768       59.8
   1152x864       60.0
   1024x768       60.0
   800x600        60.3
   640x480        59.9
DVI1 connected 1920x1080+0+0 (normal left inverted right x axis y 
axis) 443mm x 249mm
   1920x1080      60.0*+
   1024x768       70.1     60.0
   800x600        60.3     56.2
   640x480        66.7     60.0
   720x400        70.1
TV1 disconnected (normal left inverted right x axis y axis)
-- 
Wolfgang