diff --git a/lib/timeline/component/BackgroundGroup.js b/lib/timeline/component/BackgroundGroup.js
index af1286d5..ae44551c 100644
--- a/lib/timeline/component/BackgroundGroup.js
+++ b/lib/timeline/component/BackgroundGroup.js
@@ -22,10 +22,10 @@ BackgroundGroup.prototype = Object.create(Group.prototype);
  * Repaint this group
  * @param {{start: number, end: number}} range
  * @param {{item: {horizontal: number, vertical: number}, axis: number}} margin
- * @param {boolean} [restack=false]  Force restacking of all items
+ * @param {boolean} [forceRestack=false]  Force restacking of all items
  * @return {boolean} Returns true if the group is resized
  */
-BackgroundGroup.prototype.redraw = function(range, margin, restack) {
+BackgroundGroup.prototype.redraw = function(range, margin, forceRestack) {
   var resized = false;
 
   this.visibleItems = this._updateItemsInRange(this.orderedItems, this.visibleItems, range);
diff --git a/lib/timeline/component/Group.js b/lib/timeline/component/Group.js
index 58920dfa..095262ea 100644
--- a/lib/timeline/component/Group.js
+++ b/lib/timeline/component/Group.js
@@ -15,6 +15,7 @@ function Group (groupId, data, itemSet) {
   this.subgroupOrderer = data && data.subgroupOrder;
   this.itemSet = itemSet;
   this.isVisible = null;
+  this.stackDirty = true; // if true, items will be restacked on next redraw
   
   if (data && data.nestedGroups) {
     this.nestedGroups = data.nestedGroups;
@@ -212,12 +213,12 @@ Group.prototype.getLabelWidth = function() {
  * Repaint this group
  * @param {{start: number, end: number}} range
  * @param {{item: {horizontal: number, vertical: number}, axis: number}} margin
- * @param {boolean} [restack=false]  Force restacking of all items
+ * @param {boolean} [forceRestack=false]  Force restacking of all items
  * @return {boolean} Returns true if the group is resized
  */
-Group.prototype.redraw = function(range, margin, restack) {
+Group.prototype.redraw = function(range, margin, forceRestack) {
   var resized = false;
-
+ 
   // force recalculation of the height of the items when the marker height changed
   // (due to the Timeline being attached to the DOM or changed from display:none to visible)
   var markerHeight = this.dom.marker.clientHeight;
@@ -228,9 +229,9 @@ Group.prototype.redraw = function(range, margin, restack) {
       if (item.displayed) item.redraw();
     });
 
-    restack = true;
-  }
-
+    forceRestack = true;
+  }  
+  
   // recalculate the height of the subgroups
   this._calculateSubGroupHeights(margin);
 
@@ -240,12 +241,15 @@ Group.prototype.redraw = function(range, margin, restack) {
   this.right = foreground.offsetLeft;
   this.width = foreground.offsetWidth;
 
+  var lastIsVisible = this.isVisible;
   this.isVisible = this._isGroupVisible(range, margin);
-  // reposition visible items vertically
-  if (typeof this.itemSet.options.order === 'function') {
-    // a custom order function
+  
+  var restack = forceRestack || this.stackDirty || (this.isVisible && !lastIsVisible);
 
-    if (restack) {
+  // if restacking, reposition visible items vertically 
+  if(restack) {
+    if (typeof this.itemSet.options.order === 'function') {
+      // a custom order function
       // brute force restack of all items
 
       // show all items
@@ -264,23 +268,24 @@ Group.prototype.redraw = function(range, margin, restack) {
         return me.itemSet.options.order(a.data, b.data);
       });
       stack.stack(customOrderedItems, margin, true /* restack=true */);
-    }
-
-    this.visibleItems = this._updateItemsInRange(this.orderedItems, this.visibleItems, range);
-  }
-  else {
-    // no custom order function, lazy stacking
+      this.visibleItems = this._updateItemsInRange(this.orderedItems, this.visibleItems, range);
 
-    this.visibleItems = this._updateItemsInRange(this.orderedItems, this.visibleItems, range);
-
-    if (this.itemSet.options.stack) { // TODO: ugly way to access options...
-      stack.stack(this.visibleItems, margin, restack);
     }
-    else { // no stacking
-      stack.nostack(this.visibleItems, margin, this.subgroups, this.itemSet.options.stackSubgroups);
+    else {
+      // no custom order function, lazy stacking
+      this.visibleItems = this._updateItemsInRange(this.orderedItems, this.visibleItems, range);
+
+      if (this.itemSet.options.stack) { // TODO: ugly way to access options...
+        stack.stack(this.visibleItems, margin,  true /* restack=true */);
+      }
+      else { // no stacking
+        stack.nostack(this.visibleItems, margin, this.subgroups, this.itemSet.options.stackSubgroups);
+      }
     }
+    
+    this.stackDirty = false;
   }
-	
+
   this._updateSubgroupsSizes();
 
   // recalculate the height of the group
@@ -435,7 +440,7 @@ Group.prototype.hide = function() {
 Group.prototype.add = function(item) {
   this.items[item.id] = item;
   item.setParent(this);
-
+  this.stackDirty = true;
   // add to
   if (item.data.subgroup !== undefined) {
     this._addToSubgroup(item);
@@ -540,6 +545,7 @@ Group.prototype.resetSubgroups = function() {
 Group.prototype.remove = function(item) {
   delete this.items[item.id];
   item.setParent(null);
+  this.stackDirty = true;
 
   // remove from visible items
   var index = this.visibleItems.indexOf(item);
diff --git a/lib/timeline/component/ItemSet.js b/lib/timeline/component/ItemSet.js
index 8971d396..230e8781 100644
--- a/lib/timeline/component/ItemSet.js
+++ b/lib/timeline/component/ItemSet.js
@@ -155,7 +155,6 @@ function ItemSet(body, options) {
   this.groupIds = [];
 
   this.selection = [];  // list with the ids of all selected nodes
-  this.stackDirty = true; // if true, all items will be restacked on next redraw
 
   this.popup = null;
 
@@ -418,7 +417,6 @@ ItemSet.prototype.setOptions = function(options) {
  */
 ItemSet.prototype.markDirty = function(options) {
   this.groupIds = [];
-  this.stackDirty = true;
 
   if (options && options.refreshItems) {
     util.forEach(this.items, function (item) {
@@ -617,12 +615,11 @@ ItemSet.prototype.redraw = function() {
   var visibleInterval = range.end - range.start;
   var zoomed = (visibleInterval != this.lastVisibleInterval) || (this.props.width != this.props.lastWidth);
   var scrolled = range.start != this.lastRangeStart;
-  if (zoomed || scrolled) this.stackDirty = true;
+  var forceRestack = (zoomed || scrolled);
   this.lastVisibleInterval = visibleInterval;
   this.lastRangeStart = range.start;
   this.props.lastWidth = this.props.width;
 
-  var restack = this.stackDirty;
   var firstGroup = this._firstGroup();
   var firstMargin = {
     item: margin.item,
@@ -636,17 +633,16 @@ ItemSet.prototype.redraw = function() {
   var minHeight = margin.axis + margin.item.vertical;
 
   // redraw the background group
-  this.groups[BACKGROUND].redraw(range, nonFirstMargin, restack);
+  this.groups[BACKGROUND].redraw(range, nonFirstMargin, forceRestack);
 
   // redraw all regular groups
   util.forEach(this.groups, function (group) {
     var groupMargin = (group == firstGroup) ? firstMargin : nonFirstMargin;
-    var groupResized = group.redraw(range, groupMargin, restack);
+    var groupResized = group.redraw(range, groupMargin, forceRestack);
     resized = groupResized || resized;
     height += group.height;
   });
   height = Math.max(height, minHeight);
-  this.stackDirty = false;
 
   // update frame height
   frame.style.height  = asSize(height);
@@ -978,7 +974,6 @@ ItemSet.prototype._onUpdate = function(ids) {
   }.bind(this));
 
   this._order();
-  this.stackDirty = true; // force re-stacking of all items next redraw
   this.body.emitter.emit('_change', {queue: true});
 };
 
@@ -1008,7 +1003,6 @@ ItemSet.prototype._onRemove = function(ids) {
   if (count) {
     // update order
     this._order();
-    this.stackDirty = true; // force re-stacking of all items next redraw
     this.body.emitter.emit('_change', {queue: true});
   }
 };
@@ -1540,7 +1534,6 @@ ItemSet.prototype._onDrag = function (event) {
           //make sure we stay in bounds
           newOffset = Math.max(0, newOffset);
           newOffset = Math.min(me.groupIds.length-1, newOffset);
-
           itemData.group = me.groupIds[newOffset];
         }
       }
@@ -1553,8 +1546,7 @@ ItemSet.prototype._onDrag = function (event) {
         }
       }.bind(this));
     }.bind(this));
-
-    this.stackDirty = true; // force re-stacking of all items next redraw
+	
     this.body.emitter.emit('_change');
   }
 };
@@ -1607,7 +1599,6 @@ ItemSet.prototype._onDragEnd = function (event) {
           }
 
           // force re-stacking of all items next redraw
-          me.stackDirty = true;
           me.body.emitter.emit('_change');
         });
       }
@@ -1624,7 +1615,6 @@ ItemSet.prototype._onDragEnd = function (event) {
             // restore original values
             props.item.setData(props.data);
 
-            me.stackDirty = true; // force re-stacking of all items next redraw
             me.body.emitter.emit('_change');
           }
         });
diff --git a/lib/timeline/component/item/Item.js b/lib/timeline/component/item/Item.js
index 30c0bbc8..9bfa662d 100644
--- a/lib/timeline/component/item/Item.js
+++ b/lib/timeline/component/item/Item.js
@@ -64,6 +64,7 @@ Item.prototype.setData = function(data) {
   if (groupChanged && this.parent != null) {
     this.parent.itemSet._moveToGroup(this, data.group);
   }
+  this.parent.stackDirty = true;
   
   var subGroupChanged = data.subgroup != undefined && this.data.subgroup != data.subgroup;
   if (subGroupChanged && this.parent != null) {
@@ -78,7 +79,7 @@ Item.prototype.setData = function(data) {
 
 /**
  * Set a parent for the item
- * @param {ItemSet | Group} parent
+ * @param {Group} parent
  */
 Item.prototype.setParent = function(parent) {
   if (this.displayed) {