Comment 38 for bug 403610

Here's my workaround (from a terminal window):

$ # Determine what the output names are:
$ xrandr
Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 2560 x 1024
DVI-1 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
   1280x1024 60.0*+ 75.0 60.0*
   1280x960 60.0
   1152x864 75.0
   1024x768 75.0 70.1 60.0
   832x624 74.6
   800x600 72.2 75.0 60.3 56.2
   640x480 75.0 72.8 66.7 59.9
   720x400 70.1
DVI-0 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
   1280x1024 60.0*+ 75.0 60.0*
   1280x960 60.0
   1152x864 75.0
   1024x768 75.0 70.1 60.0
   832x624 74.6
   800x600 72.2 75.0 60.3 56.2
   640x480 75.0 72.8 66.7 59.9
   720x400 70.1

$ # Set up a side-by-side display
$ xrandr --output DVI-0 --left-of DVI-1
$ # Oops! It put my monitors on the wrong sides of each other
$ xrandr --output DVI-1 --left-of DVI-0