Matt,

Try to add NODEFAULT to keypress.

if lastkey()=-1
   do something
   thisform.refresh()
   NODEFAULT
endif

>We commonly use function keys (typically F2) in our apps to display a selection list lookup for field values (account numbers, job numbers etc). We do this by having the following code:
>
>Form init:
>* set function keys to default action
>on key
>
>Field When:
>*nothing (used to be on key label F2 do something)
>
>KeyPress:
>* trap the function key and perform the lookup
>if lastkey()=-1
> do something
> thisform.refresh()
>endif
>
>Valid:
>* prevent loss of focus from this field
>if lastkey()=-1
> return
>endif
>
>If the txt field has a format string of "!" (transform input to upper case), and on key has been issued already (to set function keys to default values), the character chr(159) gets inserted into the txt field. Without the format=! it doesn't happen.
>
>Our work-around is to go through every form and remove the ! from the format string, and put !!!... in InputMask instead - a real pain.
>
>Any thoughts?
>
>Cheers, Matt.