I wanted to automatically configure second monitor plugged into my laptop as above internal LCD, and I was prepared to allocate few days for this task. But, in recent X.org servers this has gotten much better, so it's enough just to add following to .xinitrc:
xrandr --output DVI-0 --auto --above LVDS xrandr --output VGA-0 --above LVDS
There is also grandr (with package in Debian) if you want point-and-click functionality.
Don't work on single monitor, having dual monitor again is such productivity boost :-)
Update: this works only on cards which report more than one output connected with xrandr -q:
Screen 0: minimum 320 x 200, current 1920 x 2250, maximum 1920 x 2250 VGA-0 disconnected (normal left inverted right x axis y axis) LVDS connected 1400x1050+0+1200 (normal left inverted right x axis y axis) 305mm x 228mm DVI-0 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 474mm x 296mmIm my case, it's ATI Technologies Inc M52 [Mobility Radeon X1300] with radeon driver. To make this work, I also needed to create virtual desktop which is large enough to accomodate both screens by adding Virtual to /etc/X11/xorg.conf:
Section "Screen"
Identifier "MyScreen"
Device "MyCard"
DefaultDepth 24
SubSection "Display"
Virtual 1920 2250
EndSubSection
EndSection