Screen spanning by accident

This afternoon I connected a new projector (Dell 3400mp) to my G4 iBook which was asleep. When I flipped up the screen I had no desktop icons, just the background picture. I couldn't figure out why until I moved the mouse to the right and it disappeared off the right hand side of the screen. I turned on the projector and sure enough there were my icons, dock, etc. My iBook was spanning two screens! I could drag iTunes from one to the other. Life was good. Then I quit iTunes and the screen reset and would only mirror after that. I relaunched iTunes, but still the screen would only mirror.

Has anyone seen this before? I thought only PowerBooks did screen spanning. Why would iTunes have anything to do with it?

Looking for input. Thanks.

Well you can get the ibooks to screen span using a tool, so technically they DO have the capability...

It is some restriction in the software that doesn't permit you from activating it.
So I suppose some glitch occured that 'accidently' enabled it.

Its the option of turning the mirroring off. If your display pref is in the top right of your screen, hit detect displays, then turn mirrorin off. This is from memory, because the computer I teach on uses a projector as well. Not an iBook though, and itunes has nothing to do with it, its like have dual monitors set up.