The Edit Menu contains the following commands. Commands which are not currently available are greyed out.
Undo - Shortcut Ctrl+Z - Undo the last change made to the current PhotoCollection Document. PhotoFrame Manager keeps a list of changes made to each open PhotoCollection Document so you can usually undo numerous levels of changes. The Undo list is discarded when you close the PhotoCollection Document.
Redo - Shortcut Ctrl+Y - Redo the last undone change to the current PhotoCollection Document.