A document's background is shown when the document has any transparent or semi-transparent pixel. Setting a custom background makes it easy to spot these transparent pixels and to test the image with different surrounding colors and patterns.
Pikselo has four different types of background that can be set to a document:
A pattern of alternating colored diagonal stripes.
A solid color painted uniformly through all the background.
A pattern of alternating colored squares that resembles a checker board.
An images stretched to the document's borders.
To change a document's background settings:
From the main window, choose View ▸ Background Settings… to open the Background Settings dialog.
On the left, there is the list of available background types. The background labeled Current is the background the document had when the dialog was open. To select a different background type, double click on an item in the list.
On the right, there are the controls to change the selected background's settings. Each background has different controls, but each one has a preview widget that shows the effect when changing the background's settings.
Click on the Close button to close the dialog
To be able to undo the changes, it is best to leave the Current settings untouched and select a different background's template.