Description of the Feature: Just a normal Undo/redo. Code for Implementation: Mockups: Just a shortcut key (ctrl + z); Why is this feature good? This feature is great because of the following: No worries about what event command you've been deleted. No more copying of an certain event before editing it (If too much long). Possible issues with this feature? Issues that might arise from this feature: Maybe there's something wrong if undo/redo for event page or undo/redo for event commands.