function toggleDropdown(panel) 
			{
				// toggle the requested one
				Element.toggle(panel);
				
				// then hide all of the others so that only
				// one (at most) is open at a time
				$$('body .dd_option_panel').each(function(node){
					if (node != $(panel)) {						
						Element.hide(node);
					}
				});	
			}