function addOption(selectId, txt, val){
	var objOption = new Option(txt, val);
	document.getElementById(selectId).options.add(objOption);
}

function showHide(id){
	if (document.getElementById && document.getElementById(id)){
		if (document.getElementById(id).style.visibility == "visible"
			|| document.getElementById(id).style.display == "block"){
			// hide it
			document.getElementById(id).style.visibility = "hidden";
			document.getElementById(id).style.display = "none";
		}else{
			// show it
			document.getElementById(id).style.visibility = "visible";
			document.getElementById(id).style.display = "block";
		}                      
	}
}

function ChangeImage(imgId, newSrc, id){
	document.getElementById(imgId).src=newSrc;
	document.getElementById(imgId).className=id;
}

function display(id, action, display_type){
	if (display_type = ''){
		display_type = 'block';
	}
	
	var elm = document.getElementById(id);
	
	switch (action){
		case 'show':
			elm.style.display = display_type;
		break;
		case 'hide':
			elm.style.display = 'none';
		break;
		default:
			if (elm.style.display == display_type){
				elm.style.display = 'none';
			}
			else{
				elm.style.display = display_type;
			}
		break;
	}
}

function getElementsByClassName(strClassName, obj){
	var ar = arguments[2] || new Array();
	var re = new RegExp("\\b" + strClassName + "\\b", "g");
	
	if (re.test(obj.className)){
		ar.push(obj);
	}
	for ( var i = 0; i < obj.childNodes.length; i++ ){
		getElementsByClassName(strClassName, obj.childNodes[i], ar);
	}
	
	return ar;
}

function check_all(class_name){
	var elements = getElementsByClassName(class_name, document.body);
	
	for (i = 0; i < elements.length; i++){
		elements[i].checked = true;
	}
}

function uncheck_all(class_name){
	var elements = getElementsByClassName(class_name, document.body);
	
	for (i = 0; i < elements.length; i++){
		elements[i].checked = false ;
	}
}