Define a private variable in the form or PRG that calls your report. (In this example, I'll use lWasPrinted.) Initialize this variable to .F. Then add a UDF in either the report summary band (or the page footer if you don't have a summary band). In the UDF, have the following code:

IF WEXIST('Printing...')
    lWasPrinted = .T.
ENDIF

Then, when they return from the preview, you can check if lWasPrinted is .T. or .F.

>Is it possile to know whether the report is printed or not
>I have code to print invoice, Once invoice printed, then the stock
>will be increased. I have two choice, User can preview the invoice before it printed. But the problem is it have the default print button
>So I can detect user to press that button to print. Can I detect it ?
>How?