I think that's a very great feature. Before that, when I accidently deleted a line or a fibonacci pattern, I had to close the entire chart without saving and reopen it, hoping my drawings was still there. I was asking for this feature many years ago already.Quote from Blotto:
Undo / Redo
What sort of "trader" would find this feature useful? Hopefully not one trusted to enter orders! There is no "undo" feature in the markets. (with the possible exception of breaking that part of a fat finger error which was done at an unreasonable price)
Of course this won't help one's fat finger mistakes while entering orders.