var state = 'none';

function showSubMenu()
{
	if(state == 'none') {
		state = 'block';
	}

	else {
		state = 'none';
	}
	
	document.getElementById('sub_menu1').style.display = state;
	document.getElementById('sub_menu2').style.display = state;
	document.getElementById('sub_menu3').style.display = state;
	document.getElementById('sub_menu4').style.display = state;
	document.getElementById('sub_menu5').style.display = state;
}