I don't know how simple this answer is......my suspicion is you won't be
able to do this (I don't think), or at least not without a little effort and
digging into the HTML (if you're comfortable doing that).
I would think you'd need to use one of the following methods (I don't know
which would work) but you'd need to use the onsubmit() event to call the jim
code script, but even then it probably won't work since the confirmation
page loads through the internal workings of the server extensions, not
through editable code and you can't change that. However you could test
this method and see what you can accomplish.
eg <input type="submit" name="Send" value="Send Message"
onsubmit(whatever);>
or
<form name="mail" action="whatever...." method="post"
onsubmit(whatever....);>
I'd just build a popup through the wizard in the plugin in the normal way,
then look at the code generated, and place the bit from the "onclick" link
to the "onsubmit" bit in (either) the <form> or <input> tag.
However Jimco would be able to answer this for sure; in the normal course of
things, that script uses a normal onclick event or onload event. Why the
need specifically, for a "popup" window for the confirmation page?
If you don't like the standard page, you can customise the design (create
your own page and specify it in the form properties) to suit your site
design.
The other thing I can suggest is make the popup happen first i.e. a link
that opens the popup window with the form, then the confirmation page will
appear (in the same window). As above you can customise it. and then you
can say "Thank you - data submitted" and put a "Click here to close window"
link or whatever you like.
