while measuring my moms kitchen i was drawing polyline as we were measuring distances… when i wanted to correct my point i hit undo ctrl z, it got be one control point back which is OK but then i clicked ctrl y to redo that point and suddenly whole polyline was GONE ! we could start over with our measurements …
Yep, I see that. No idea if anything can be done about that.
Yeah, Undo is a thing in Polyline, Redo is not. Ctrl-Y is defined as ! _Redo so of course it cancels the currently running command. You might try makiing that just “_Redo” so at least you won’t kill the command in this sort of situation, even if it does not redo.
-Pascal
i will leave it to your assesment if current behaviour is as it should be or could be somehow improved. I am midst having fun right now 
. There will be cookies eventually as reward