enter a "Code" out of range. (I entered "0x" - no digits - for other ctrl characters)
switch away from slickedit.
switch back.
Slick prompts "Please input a char code between 1 and 255"
(Nit: I was in hex mode, so it should be 0x01 to 0xff).
Slick continues to prompt about this, I can't get it to stop so I can't fix the number :-(
Oh....holding "ESC" and letting it auto-repeat manages to get this dialog to stay closed.