function showhide() {
	var id = "dropdown";
	var state = document.getElementById(id).style.display;  
	if (state == 'block') document.getElementById(id).style.display = 'none';
	else document.getElementById(id).style.display = 'block';
	return false;
}  
window.onload = function() { 
	var menuTrigger = document.getElementById("menuTrigger");
	menuTrigger.onclick = showhide;
};