Oracle Forms

I am generating a file from oracle forms and writing it out to the client machine. I am able to successfully create the file and close it. If on the offchance that a user tries to regenerate the file while it is open, the form hangs. Therefore, I want to check to see if it is open and if so display an error to the user and Raise Form_Trigger_Failure etc...

I am calling the webutil function like this:

IF Client_Text_IO.IS_OPEN(v_filename) THEN
error
Else
generate file
End if;

I have tried declaring v_filename as a Varchar2 and as a Client_Text_IO.File_Type to no avail. Is there a way I can check to ensure that the file is not open when the button to generate it is pressed?

Thanks,
c