How can I detect non-hidden pdfs?

Hi,

I want to only apply event to non-hidden files.  I tried the following but it did not bring up the app alert when I had a non-hidden pdf file in the sequence.  What am I doing wrong?  I know it must have something to do with the bolded text.

if (this.hidden = false)

{

if (3 == app.alert("Before proceeding, confirm scanned documents were backed up.  If not, click No to close the program and backup the scanned documents before executing the program.",1,2))

{

event.rc = false;

}

}