I’ve noticed that when you’re you have Design Mode turned off, and Interaction toggled on; that Undos don’t work. Some times it takes me a second or two to realize that; I wouldn’t mind a warning sign popping up to remind me to turn off Interaction to Undo; ideally not a pop-up that I’d have to click; maybe just a visual cue that the keyboard action that I just didn’t isn’t going to work.