Empty image pattern

[Chris Carroll-Davis]

Hello folks.

Real newbie question here...  If I create an image it's empty.  Fine, 
that's what I want.  I can put a picture in it.  Fine.  But how do I 
get back to the clear image box again!!??  If I set the filename to 
empty I get a checkerboard pattern that I can only get rid of by 
setting another valid filename.  I want to able to get back to a clear 
image box!!

I must be missing something obvious...  any suggestions?

Chris