So the <form action=> does *NOT* specify "selection.asp"? That is, you are using another page to process the form posting?
Have you considered using AJAX to post the form, so you don't have to reload the page, which must be a slow process given the multiple tabs?
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.