Finally, there are three basic functions which you should add to your stock of familiar commands.
To abort any command which requires you to type information at the echo area, type
Ctrl+G at any point up to where you would normally press
Return. For instance, if you type
Ctrl+X Ctrl+F in order to open a file, and then decide against it, type
Ctrl+G instead of specifying a filename.
If you choose Edit > Undo the last editor action performed is undone. Successive use of Edit > Undo revokes more actions (rather than undoing the last Undo command, as is the case with many other editors).
LispWorks IDE User Guide (Unix version) - 13 Sep 2017