SendToEditor problems with 4.4

A question in advance: Is there already a difference between 4.4 and 4.5-alpha-35846?

I realized that after updating (to 4.4) some of my upload functions within custom meta boxes are not working anymore.

This is my current js – which still opens the media library but doesn’t send the img src to my input field anymore
……………………….

var uploadID = '';
var storeSendToEditor = '';
var newSendToEditor   = '';
jQuery('.customupload').live('click', function() {
    window.send_to_editor = newSendToEditor;
    uploadID = jQuery(this).prev('input');
    wp.media.editor.open(this);
    return false;
});
storeSendToEditor = window.send_to_editor;
newSendToEditor  = (function(html) {
    imgurl = jQuery('img',html).attr('src');
    uploadID.val(imgurl);
    tb_remove();
});

…………………….

if I change …
=> wp.media.editor.open(this);

… into an elder version (< 3.5) …
=> tb_show( ”, ‘media-upload.php?type=image&TB_iframe=true’ );

… it’s working again and the my input is filled with the img src again. (using the old media library style/functions)

I’ve tested the whole thing on a second website, using the latest WP Release (with Beta Tester Plugin) which is “WordPress 4.5-alpha-35846”. Surprisingly every upload function using the first code above is working without any problems.

So is there in fact a difference between these WP versions or am I just doing something completely wrong? And the “sendToEditor” results I’ve seen are somehow random?

Any help or hint is highly appreciated – thanks a lot in advance!