removed div id from navigation

HISTORY.md

@@ -18,6 +18,7 @@ http://visjs.org
 ### Timeline
 
 - Added a finishedRedraw event.
+- Fixed the disappearing item bug.
 
 ## 2014-11-07, version 3.6.4
 

lib/network/mixins/NavigationMixin.js

@@ -13,9 +13,8 @@ exports._cleanNavigation = function() {
   this._navigationReleaseOverload = function () {};
 
   // clean up previous navigation items
-  var wrapper = document.getElementById('network-navigation_wrapper');
-  if (wrapper && wrapper.parentNode) {
-    wrapper.parentNode.removeChild(wrapper);
+  if (this.navigationDivs && this.navigationDivs['wrapper'] && this.navigationDivs['wrapper'].parentNode) {
+    this.navigationDivs['wrapper'].parentNode.removeChild(this.navigationDivs['wrapper']);
   }
 };
 
@@ -35,7 +34,6 @@ exports._loadNavigationElements = function() {
   var navigationDivActions = ['_moveUp','_moveDown','_moveLeft','_moveRight','_zoomIn','_zoomOut','_zoomExtent'];
 
   this.navigationDivs['wrapper'] = document.createElement('div');
-  this.navigationDivs['wrapper'].id = 'network-navigation_wrapper';
   this.frame.appendChild(this.navigationDivs['wrapper']);
 
   for (var i = 0; i < navigationDivs.length; i++) {

lib/timeline/component/Group.js

@@ -405,7 +405,7 @@ Group.prototype.order = function() {
  */
 Group.prototype._updateVisibleItems = function(orderedItems, oldVisibleItems, range) {
   var visibleItems = [];
-  var visibleItemsLookup = {};
+  var visibleItemsLookup = {}; // we keep this to quickly look up if an item already exists in the list without using indexOf on visibleItems
   var interval = (range.end - range.start) / 4;
   var lowerBound = range.start - interval;
   var upperBound = range.end + interval;