Undo/Redo and History

Undo: Select menu: Edit -> Undo [Ctrl+Z] to perform an undo action, you can perform unlimited undo actions like this.

Redo: Select menu: Edit -> Redo [Ctrl+Shift+Z] to perform a redo action, you can perform unlimited redo actions like this.

Save History: Select menu: Edit -> Save Expression in History[Ctrl+S] to save current expression as a history item.

Recall previous History Item: Select menu: Edit -> Load Previous in History [Ctrl+Up] to recall previous history item in history.

Recall next History Item: Select menu: Edit -> Load Next in History[Ctrl+Down] to recall next history item in history.