form opening popup and graying out page

How can I make a form that on submit (method=post)
it opens up a centered popup the height and width I want and then grays out the current page until the popup is closed?

Grayout effect is only for IE.

On submitting -

1 open popup window using window.open and Make the page gray using grayout() function provided below.


function grayout()
{
ht = document.getElementsByTagName("html");
ht[0].style.filter = "progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)";
}


2. on poup window, make an ungrayout and onunload functions below.


function ungrayout()
{
ht = window.opener.document.getElementsByTagName("html");
ht[0].style.filter = "";
}
onunload = ungrayout;