(function($) {

	$.extend({
		add2cart: function(source_id, target_id, callback) {
    
      var source = $('#' + source_id );
      var target = $('#' + target_id );
      
      var shadow = $('#' + source_id + '_shadow');
      if( !shadow.attr('id') ) {
          $('body').prepend('<div id="'+source.attr('id')+'_shadow" style="display: none; background-color: #eee; border: solid 1px #ddd; position: static; top: 0px; z-index: 100000;">&nbsp;</div>');
          var shadow = $('#'+source.attr('id')+'_shadow');
      }
      
      if( !shadow ) {
          alert('Cannot create the shadow div');
      }
      
      shadow.width(source.css('width')).height(source.css('height')).css('top', source.offset().top).css('left', source.offset().left).css('opacity', 0.8).show();
      shadow.css('position', 'absolute');
      shadow.animate( {
		width: target.innerWidth(), 
		height: target.innerHeight(),
		top: target.offset().top, 
		left: target.offset().left },{duration: 1000} ).animate( { opacity: 0 }, { duration: 200, complete: callback });

shadow.animate({  "left": "-9999", "opacity": 0  }, { duration: 20, complete: callback });

        
		}

		   
	});
})(jQuery);