function showElement(elementId) {

	var element = document.getElementById(elementId);
	if (element != undefined && element.style.display != "block") {
	    element.style.display = "block";
	}
}

function hideElement(elementId) {

	var element = document.getElementById(elementId);
	if (element != undefined && element.style.display != "none") {
	    element.style.display = "none";
	}
}