function appear(obj_id) {
			if (document.getElementById){
				var obj = document.getElementById(obj_id);
				if (obj.style.display == '' || obj.style.display == 'none'){
					var state = 'block';
					obj.style.display = state;
				} 
				
			}
		}

function disappear(obj_id) {
			if (document.getElementById){
				var obj = document.getElementById(obj_id);
				if (obj.style.display == 'block'){
					var state = 'none';
					obj.style.display = state;

				} 
				
			}
		}