post the form data in modal window and close the modal window.

In the following code, when user clicks Validate button in page1.asp,
it will open
page2.asp as a modal window. When the user click submit button in
page2.asp,
I expect to open page page3.asp as in page2.asp. However, it opens a
new
window for page3.asp. I guess this is because page2.asp is in modal
window.

What I want is: when the user clicks submit button in page2.asp, it
will
submit the form and open page3.asp, and closes page2.asp. What are the
workarounds to my problem? Thanks!!

=================== page1.asp ========================================

function openWindow()
{
var params;
var sReturn = window.showModalDialog("page2.asp",params,"dialogH eight:500px;
dialogWidth:500px;");
}

<INPUT type="button" value="Validate" name="PopulateButton"
onClick="openWindow()">

================== page2.asp
==========================================

<FORM NAME="InputForm" ACTION="page3.asp" METHOD="POST">