code: function visible( element ) {
  		// check if one of the parents (until it's position parent) is invisible
  		// prevent that elements in static area are always checked as invisible
  
  		// list all items until the offsetParent item (with jQuery >1.6 you can use parentsUntil)
  		var oOffsetParent = jQuery(element).offsetParent();
  		var bOffsetParentFound = false;
  		var $refs = jQuery(element).parents().filter(function() {
  			if (this === oOffsetParent) {
  				bOffsetParentFound = true;
  			}
  			return bOffsetParentFound;
  		});
  
  		// check for at least one item to be visible
  		return !jQuery(element).add($refs).filter(function() {
  			return jQuery.css( this, "visibility" ) === "hidden" || jQuery.expr.filters.hidden( this );
  		}).length;
  	}
docs: /*!
  The following functions are taken from jQuery UI 1.8.17 but modified
  
  Copyright 2011, AUTHORS.txt (http://jqueryui.com/about)
  Dual licensed under the MIT or GPL Version 2 licenses.
  http://jquery.org/license
  
  http://docs.jquery.com/UI