Getting out of file requesters

Help !!.

If I've got a file requester window, ready for the user to select a file - but they decide to cancel it, by clicking on the close X.

How can I poll for it, the request command doesnt register a sucessfull selection ?

I dont mean that the file was sucessfully loaded - but that the user selected a valid file using the requester ??.

Sorry, worked this one out myself - slap to side of head !.

I only had to check the filename string to see if it contained anything. DOH !