function removeNullCategory(){
		//decided for those do not hv record's category
		//for example, mono-ringtone
		var x=document.getElementById("category");
		if(x){
			var child = x.getElementsByTagName("LI");
			for(var i=0; i<child.length; i++){
				if(child[i].getElementsByTagName("A")[0].innerHTML.length<1){
					child[i].style.display = 'none';
				}
			}
		}
}

function addBlankCategory(){
		var x=document.getElementById("category");
		if(x){			
			var child = x.getElementsByTagName("LI");
			var blankLI = '';
			for (var i=0; i<(3-(child.length%3)); i++ ){
				blankLI += '<LI class="category_blank"><a>&nbsp;</a></LI>';
			}
			x.getElementsByTagName("UL")[0].innerHTML +=blankLI;
		}
}