Please stop reviving this off-topic discussion. The mIRC built-in script editor uses Ctrl+Y for undo. Nothing else is relevant.
Let's reserve future posts in this thread for discussion related to the original feature suggestion.
This is correct so I was wrong about the shortcut used in mIRC. Like Ramius it's hard to remember which shortcut does what. CNTRL-Z is Undo. We we're all right about that.
I agree with the original post...