rem: child.style.visibility = 'hidden'; 
add: if (child) { child.style.visibility = 'hidden'; } 
context: function hideMenu( child ) { 	child.style.visibility = 'hidden'; } 
meta: 10023	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10023/f113b7ea4c5e8e308259bc4bb7bbc1c1bf34895d/Top Nav Dropdown.js/clean/trunk/modules/navigationmodule/js/Top Nav Dropdown.js