WL 7.2 rather minor bug - F3,F4

maybe bug is a word too big…in wl 7.1 i customized the key-commands for Undo, Redo to F3 & F4. after the program was patched to 7.2, F3 & F4 did not work any more. went to Options -> Customize Commands, and found ctrl+Z & crtl+shift+Z should do the job. and they did.
tried to change these settings again: in the field with the entry ctrl+Z i typed in F3. the field got yellow highlighted with the note that F3 is already in use…for Undo…well, i insisted on F3, clicked ok and F3 is working again like it should. so the note, that F3 (or F4 respectively) is already in use, is senseless or wrong.
no big thing.