ATI

Nuke all the deprecated cruft from the xorg.conf file. So that's the HorizSync and VertRefresh from Monitor sections, and any manual Xinerama or dual head configs.

Add a Virtual line to the Display section:

Section "Screen"
    Identifier      "Default Screen"
    Device          "ATI 200M"
    Monitor         "Laptop Display"
    DefaultDepth    24
    SubSection "Display"
        Modes       "1280x768"
        Virtual     1280 1536
    EndSubSection
EndSection

Then use xrandr to wake up the other end of the DBUS cable:

xrandr --output VGA-0 --set load_detection 1

Clone the desktop:

xrandr --output VGA-0 --auto --mode 1280x768

Or extend the desktop:

xrandr --output VGA-0 --auto --mode 1280x768 --above LVDS

Links

Unexplored option for an ACPI script on Fn-F7 key.