How do I stop my wallpapers from moving about when I turn off one of my three monitors?
This is very annoying.

I have 3 monitors... two for working (on my desk - DVI and VGA) and one for teaching (HDMI about 10 yards away).
Each has it's own wallpaper.

When I'm not teaching I turn off the TV screen leaving me with just my two work monitors.
But each time I do, my wallpapers move about.

When I turn the TV back on it's fixed... but leaving on the TV just to avoid disturbing the wallpapers seems a bit too much!

So... how do I make my wallpapers 'sticky'?