"Redo" reverses the effects of "Undo". Each "undo" action can be reversed by a single "redo" action, until the image returns to its final state; you can alternate "undo" and "redo" as much as you please. Note that "redo" is only available if the last action performed was an "undo". If you act on the image in any way after undoing something, then the states that could otherwise have been reached by redoing are lost, and there is no way to recover them. See the Undoing section for more information.

To get an undone operation back, use the Undo History dialog.