function drop1() {
	var block = document.getElementById ('menu1');
	if (block.className == 'hidden') {
	block.className='visible';
	}
}

function undrop1() {
	var block = document.getElementById ('menu1');
	if (block.className == 'visible') {
	block.className='hidden';
	}
}

function drop2() {
	var block = document.getElementById ('menu2');
	if (block.className == 'hidden') {
	block.className='visible';
	}
}

function undrop2() {
	var block = document.getElementById ('menu2');
	if (block.className == 'visible') {
	block.className='hidden';
	}
}