>Hi,
> Yes, I use this command to verify the _screen.activeform either an object or not. It works fine and not cause VFP Error. However, user will not able to perform task like save, delete and.... from toolbar for the form focused at that moment. User have to terminate the program and run it again. How could I prevent this happen ? I think it is too bad to ask user re-run the application...
>

Why don't you create an application object property, and in the Activate method of the form, set the application object property to the current form's object reference? Use that to determine what the last active form was...