I found this exchange that might point you in the right directorion:

[Report designer] Re: When someone cancels a print preview . . . Thread #128647 Message #128737
From
Edward Pikman
Broadcast Music, Inc.
08/21/1998 09:18:32 To
Mark Bucciarelli
Kko and Associates, Inc.
08/20/1998 20:07:14
>Is it possible to trap when someone has canceled a report from the print preview window? Thanks!

I guess you can use some counter property incremented by one once for the whole report:
oApp.counter=0
report form preview
? oApp.counter && 1-just previewed, 2-previewed and printed

>How can i detect the user pressed the print button on the "print preview toolbar" ?