add filter post_selection_ui_render_results_args to allow for filtering 

If I wanted to, for example, only allow parents to be connected (this example would be using this module with o2o), this filter would allow this via:

    add_filter('post_selection_ui_render_results_args', function( $query ){
    	$query['post_parent'] = 0;
    	return $query;
    });