var navArray = new Array("dropdown02", "dropdown03", "dropdown04", "dropdown05", "dropdown06", "dropdown07"); 

function expandDiv(navitem) 
{
	
	for( i=0; navArray[i]; i++ )
	{
		if( navArray[i] != navitem )
			document.getElementById(navArray[i]).style.visibility = 'hidden';
	}
	
	if( navitem )
		document.getElementById(navitem).style.visibility = 'visible';
		
}