Using alternate backgrounds
One of Pixen's more unique features is the alternate background, which displays when the cursor is outside of the document window. This can be used in any number of ways, but one example would be quickly seeing how a sprite appears against—say—a grass tile of your game by simply flicking your mouse out of the document and then back in again.
You can set an alternate background for your document in the backgrounds configurator: simply use the same procedure as for normal backgrounds but instead drag the template to the area marked "Alternate background".
If you decide later that you don't want to have an alternate background anymore, simply drag the background out of the area.
See also
Setting a document's background
Working with backgrounds
Background Topics