Background image on dual screen?

[Alan Evans]

I have two monitors an my background image is exactly the size of both
combined. I used to be able to display this background image across
both screens as if they were a single display. I think I chose "Tiled"
to make this happen, but I'm not sure it was always that way.

Anyway, after an update a few months ago, I can no longer do this. My
background image is displayed, either clipped or scaled, once on each
screen instead of once across all screens, no matter what style I
choose from the Appearance Preferences dialog. Is there a way to fix
it?

-Alan