I have created a complicated 3 page PDF form with a submit button. When the button is pressed the FDF file is sent to a PHP script on my webserver and is saved. This all works as it supposed to except when the submit button is pressed, the browser window changes and the PDF form is gone. If the user goes back to the PDF form, it is blank. If something goes wrong with the FDF upload, the user would have to fill in the PDF form all over again. Is there a way to keep the PDF form open in the browser after the FDF file is sent to my webserver?

I have tried placing:
echo "<script type='text/javascript'>;</script>";
as the first line in the PHP script. This does open a new tab but it is too late - it is after the browser switches to the new page.

I have tried placing:
window.open('','_newtab')
in the PDF file but Adobe does not support the window object.

I already have a popup that tells the user to print the form before sending it (and I have a print button on the form).