Popup-Handling at embedded browser sessions

Hi there,
when using an embedded browser session to manage sites who will use popups, these popups are opened in a new tab. This Tab can't be closed by pressing OK oder Cancel or something like that within the popup dialog.
Microsoft Exchange ECP is a good sample on this - managing an user will oben an popup which will be closed by OK or Cancel on external / normal browser sessions.
greez, markus