Saw in one site file download. There is a javascript link. When you click a new window is created with the desired size. There is a file upload form and a "add" button. There is no js in this form, but when you click "add", it completely uploads the file, refreshes the page and closes itself. And on the main page is added "tag" with its address.
JS-link on the main page
function multi_call4505() { window.open("forum_serv.php?q=6","attach","toolbar=0,width=400,height=120"); }
In the new window, the usual form with the input file
<form method="Post" action="forum_serv.php?q=7" enctype="multipart/form-data">
Interested in 2 questions, how does the main page learn about file loading and how does a child window without JS self-close?