Automatically set VGA output as "primary" in Gnome

I always liked gnome-display-properties in that by just clicking its tray icon it will enable (or disable) the VGA output of my laptop if my "secondary" LCD is connected or not. I switch to laptop-LCD only to laptop-plus-external-LCD daily. Recently I started using this external monitor as "primary", using also a external keyboard and mouse, and wanted the gnome panels (menu, taskbar, etc.) to appear there.

However, gnome-display-properties assumes the monitor at the "left" is primary, so menus are always displayed there. It has no UI, no gesture to configure it differently. Fortunately, xrandr (which I think gnome-display-properties uses) allows to freely configure evertyhing related to displays: enable/disable, geometry, layout, etc. After experimenting a little I came up with this little script:

OUT=`xrandr|grep connected|grep -v disconnected| wc -l`
if [ $OUT -gt 1 ]; then
  xrandr --output LVDS1 --auto --output VGA1 --auto --right-of LVDS1 --primary
else
  xrandr --output LVDS1 --auto --output VGA1 --off
fi

which enables my VGA output if a monitor is connected, but setting it as primary (the command line is self-explanatory). I bound this script to an unused key (the blue "ThinkVantage" key on my thinkpad) and now I switch configuration exactly as I wanted: with one key press.

Note: I played a little with XFCE4.8 and I found a different (though related) issue: panels not moving from one to the other display automatically. I asked in the forums and this is unfortunately not supported -- though it was scheduled for 4.10 as soon as I posted a ticket, as Nick from XFCE recommended.