function showMenu(elem,tagname1,tagname2,tagname3){
	var tds = document.getElementById(elem).getElementsByTagName(tagname1);
	for(var i in tds){
		tds[i].onmouseover = function(){
			if(this.getElementsByTagName(tagname3).length>0){
				this.getElementsByTagName(tagname2)[0].style.display = 'block';	
				var as = this.getElementsByTagName("a");
				for(var i=1;i<as.length;i++){
					as[i].style.width = this.offsetWidth - 18 + 'px';		
				}
			}
		}
		tds[i].onmouseout = function(){
			if(this.getElementsByTagName(tagname3).length>0){
				this.getElementsByTagName(tagname2)[0].style.display = '';		
			}
		}
	}	
}