WordPress 3.5 has been released recently, I used the WordPress Media Upload system via thickbox and window.send_to_editor for some options in my WordPress theme
I found nothing to trigger a custom function if the editor closes. I uses this:
wp.media.editor.open();
$('.media-modal-close, .media-modal-backdrop').one('click', function(){
//do some stuff
});
or better:
var id = wp.media.editor.id();
var editor = wp.media.editor.get( id );
if('undefined' != typeof( editor )) editor = wp.media.editor.add( id );
if ( editor ) {
editor.on('close', function(){
//do some stuff
});
}