How to Undo / RedoThe keyboard shortcuts work even when there's no menu available. So what are they?
For undo, it's <ctrl>z
and for redo, it's <ctrl>y
This is a shorthand way of saying that you press and hold the key marked 'ctrl' ('opt' on Macs) and while holding it press the 'z' key once. Yes, 'y' is the same.
So you can try it, I've put a Google search box below. No need to click the button (unless you want to) just type something, then undo (<ctrl>z), then redo (<ctrl>y). See, it works!
Type a couple of words, select one of them, type any old letter, then undo. See if it works on multiple 'undo's and 'redo's.
This works in ordinary Windows dialog boxes, too... also in the browser address bar. As I said, pretty much anywhere :)
I hope this one saves you cursing when you type in a load of stuff and accidentally delete it!