// vrati objekt so zadanym id
function gId(name)
  {
  return document.getElementById(name);
  }

// zobrazi menu
timer = 0;
var lastShown = '';
function showMenu(id)
	{
	hideLastMenu();

	if(gId(id))
		{
		gId(id).style.display = '';

		lastShown = id;
		clearTimeout(timer);
		//alert('killed ' + timer);
		timer = setTimeout('hideLastMenu();', 3000);
		}
	}
// zobrazi
function hideLastMenu()
	{
	if(lastShown.length > 0)
		gId(lastShown).style.display = 'none';

	lastShown = '';
	}