win.contentWindow
var wsrc = w.contentWindow
The "contentWindow" property points to the DHTML source of the inner
displayFrame of the window. In case the window has been created
with a sixth (src) parameter, this variable will point to the base DHTML
window of that source. When a WebServer request has returned, "contentWindow"
will point to the the base window of the server-generated web page
To address the first image in
a window called "w", use:
w.contentWindow.document.getElementsByTagName("img")[0]