Is there a way to have a php page submit a form just from opening another page?

Example -- Can I open a thankyou.php webpage and have it use php code to put up a "thank you for registering for this course!" for 5 seconds and then have it submit a form on another open php page without touching the other page and then have it close both the form page AND the thankyou.php page?

I was thinking maybe a flag could be set that when you open thankyou.php, it would run a php statement that would focus() on the form page and then somehow set a $flag to "formmail.php" and somehow submit that form.

Is this possible -- it sounds like that could work i just am not sure how..

Can anyone help?

Anthony