var openmenu = 0;

function opendropdown(id)
{
	if(openmenu) openmenu.style.visibility = 'hidden';

	openmenu = document.getElementById(id);
	openmenu.style.visibility = 'visible';
}

function closedropdown()
{
	if(openmenu) openmenu.style.visibility = 'hidden';
	openmenu = 0;
}