I don't understand what you want to achieve, but it seems that you want to make something happens when you move your custom element outside the document or the window.
You should try binding a handler with a dragleave
or something like that. Here is an example from another question:
var dropTarget = $('.dropTarget'),
html = $('html'),
showDrag = false,
timeout = -1;
html.bind('dragenter', function () {
dropTarget.addClass('dragging');
showDrag = true;
});
html.bind('dragover', function(){
showDrag = true;
});
html.bind('dragleave', function (e) {
showDrag = false;
clearTimeout( timeout );
timeout = setTimeout( function(){
if( !showDrag ){ dropTarget.removeClass('dragging'); }
}, 200 );
});
I think that could work for you, but for further help you should extend your issue's description.
Also I ll leave some HTML5 drag and drop docs here