(function($) {

	$.extend({
		add2cart: function(source_id, target_id) {
    
		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: #ddd; border: solid 1px darkgray; 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', 0.5).show();
		shadow.css('position', 'absolute');
		  
		shadow.animate( { width: target.innerWidth(), height: target.innerHeight(), top: target.offset().top, left: target.offset().left }, 300 )
			.animate( { opacity: 0 }, 200, function(){
				$(this).remove(); //removes shadow after animation
			} );
		
		}
	});
})(jQuery);