diff --git a/src/timeline/Timeline.js b/src/timeline/Timeline.js
index c4e79e6c..4c7f54ee 100644
--- a/src/timeline/Timeline.js
+++ b/src/timeline/Timeline.js
@@ -176,6 +176,41 @@ function Timeline (container, items, options) {
   this.contentPanel = new Panel(contentOptions);
   this.mainPanel.appendChild(this.contentPanel);
 
+  // content panel (contains the vertical lines of box items)
+  var backgroundOptions = util.extend(Object.create(this.options), {
+    top: function () {
+      return (me.options.orientation == 'top') ? (me.timeAxis.height + 'px') : '';
+    },
+    bottom: function () {
+      return (me.options.orientation == 'top') ? '' : (me.timeAxis.height + 'px');
+    },
+    left: null,
+    right: null,
+    height: function () {
+      return me.contentPanel.height;
+    },
+    width: null,
+    className: 'background'
+  });
+  this.backgroundPanel = new Panel(backgroundOptions);
+  this.mainPanel.insertBefore(this.backgroundPanel, this.contentPanel);
+
+  // panel with axis holding the dots of item boxes
+  var axisPanelOptions = util.extend(Object.create(rootOptions), {
+    left: 0,
+    top: function () {
+      return (me.options.orientation == 'top') ? (me.timeAxis.height + 'px') : '';
+    },
+    bottom: function () {
+      return (me.options.orientation == 'top') ? '' : (me.timeAxis.height + 'px');
+    },
+    width: '100%',
+    height: 0,
+    className: 'axis'
+  });
+  this.axisPanel = new Panel(axisPanelOptions);
+  this.mainPanel.appendChild(this.axisPanel);
+
   // content panel (contains itemset(s))
   var sideContentOptions = util.extend(Object.create(this.options), {
     top: function () {
@@ -398,7 +433,7 @@ Timeline.prototype.setGroups = function(groupSet) {
 
     // remove itemset if existing
     if (this.itemSet) {
-      //this.itemSet.hide(); // TODO: not so nice having to hide here
+      this.itemSet.hide(); // TODO: not so nice having to hide here
       this.contentPanel.removeChild(this.itemSet);
       this.itemSet.setItems(); // disconnect from itemset
       this.itemSet = null;
@@ -406,7 +441,7 @@ Timeline.prototype.setGroups = function(groupSet) {
 
     // create new GroupSet when needed
     if (!this.groupSet) {
-      this.groupSet = new GroupSet(this.contentPanel, this.sideContentPanel, options);
+      this.groupSet = new GroupSet(this.contentPanel, this.sideContentPanel, this.backgroundPanel, this.axisPanel, options);
       this.groupSet.on('change', this.rootPanel.repaint.bind(this.rootPanel));
       this.groupSet.setRange(this.range);
       this.groupSet.setItems(this.itemsData);
@@ -428,7 +463,7 @@ Timeline.prototype.setGroups = function(groupSet) {
     }
 
     // create new items
-    this.itemSet = new ItemSet(options);
+    this.itemSet = new ItemSet(this.backgroundPanel, this.axisPanel, options);
     this.itemSet.setRange(this.range);
     this.itemSet.setItems(this.itemsData);
     this.itemSet.on('change', me.rootPanel.repaint.bind(me.rootPanel));
@@ -504,6 +539,8 @@ Timeline.prototype.getSelection = function getSelection() {
  * @param {Date | Number | String} [start] Start date of visible window
  * @param {Date | Number | String} [end]   End date of visible window
  */
+// TODO: implement support for setWindow({start: ..., end: ...})
+// TODO: rename setWindow to setRange?
 Timeline.prototype.setWindow = function setWindow(start, end) {
   this.range.setRange(start, end);
 };
@@ -512,6 +549,7 @@ Timeline.prototype.setWindow = function setWindow(start, end) {
  * Get the visible window
  * @return {{start: Date, end: Date}}   Visible range
  */
+// TODO: rename getWindow to getRange?
 Timeline.prototype.getWindow = function setWindow() {
   var range = this.range.getRange();
   return {
diff --git a/src/timeline/component/CurrentTime.js b/src/timeline/component/CurrentTime.js
index 089a5e13..26606207 100644
--- a/src/timeline/component/CurrentTime.js
+++ b/src/timeline/component/CurrentTime.js
@@ -71,8 +71,8 @@ CurrentTime.prototype.start = function start() {
     me.stop();
 
     // determine interval to refresh
-    var scale = me.range.conversion(parent.width).scale;
-    var interval = 1 / scale / 2;
+    var scale = me.range.conversion(me.parent.width).scale;
+    var interval = 1 / scale / 10;
     if (interval < 30)   interval = 30;
     if (interval > 1000) interval = 1000;
 
diff --git a/src/timeline/component/Group.js b/src/timeline/component/Group.js
index ed81dca6..2c4043c5 100644
--- a/src/timeline/component/Group.js
+++ b/src/timeline/component/Group.js
@@ -1,16 +1,20 @@
 /**
  * @constructor Group
- * @param {Element} groupFrame
- * @param {Element} labelFrame
+ * @param {Panel} groupPanel
+ * @param {Panel} labelPanel
+ * @param {Panel} backgroundPanel
+ * @param {Panel} axisPanel
  * @param {Number | String} groupId
  * @param {Object} [options]  Options to set initial property values
  *                            // TODO: describe available options
  * @extends Component
  */
-function Group (groupFrame, labelFrame, groupId, options) {
+function Group (groupPanel, labelPanel, backgroundPanel, axisPanel, groupId, options) {
   this.id = util.randomUUID();
-  this.groupFrame = groupFrame;
-  this.labelFrame = labelFrame;
+  this.groupPanel = groupPanel;
+  this.labelPanel = labelPanel;
+  this.backgroundPanel = backgroundPanel;
+  this.axisPanel = axisPanel;
 
   this.groupId = groupId;
   this.itemSet = null;    // ItemSet
@@ -87,7 +91,7 @@ Group.prototype.setItems = function setItems(itemsData) {
   if (this.itemSet) {
     // remove current item set
     this.itemSet.setItems();
-    this.groupFrame.removeChild(this.itemSet.getFrame());
+    this.groupPanel.frame.removeChild(this.itemSet.getFrame());
     this.itemSet = null;
   }
 
@@ -101,9 +105,10 @@ Group.prototype.setItems = function setItems(itemsData) {
         return Math.max(me.props.label.height, me.itemSet.height);
       }
     });
-    this.itemSet = new ItemSet(itemSetOptions);
+    this.itemSet = new ItemSet(this.backgroundPanel, this.axisPanel, itemSetOptions);
     this.itemSet.on('change', this.emit.bind(this, 'change')); // propagate change event
-    this.groupFrame.appendChild(this.itemSet.getFrame());
+    this.itemSet.parent = this;
+    this.groupPanel.frame.appendChild(this.itemSet.getFrame());
 
     if (this.range) this.itemSet.setRange(this.range);
 
@@ -121,7 +126,11 @@ Group.prototype.setItems = function setItems(itemsData) {
  */
 Group.prototype.show = function show() {
   if (!this.dom.label.parentNode) {
-    this.labelFrame.appendChild(this.dom.label);
+    this.labelPanel.frame.appendChild(this.dom.label);
+  }
+
+  if (this.itemSet) {
+    this.itemSet.show();
   }
 
   var itemSetFrame = this.itemSet && this.itemSet.getFrame();
@@ -129,7 +138,7 @@ Group.prototype.show = function show() {
     if (itemSetFrame.parentNode) {
       itemSetFrame.parentNode.removeChild(itemSetFrame);
     }
-    this.groupFrame.appendChild(itemSetFrame);
+    this.groupPanel.frame.appendChild(itemSetFrame);
   }
 };
 
@@ -141,6 +150,10 @@ Group.prototype.hide = function hide() {
     this.dom.label.parentNode.removeChild(this.dom.label);
   }
 
+  if (this.itemSet) {
+    this.itemSet.hide();
+  }
+
   var itemSetFrame = this.itemset && this.itemSet.getFrame();
   if (itemSetFrame && itemSetFrame.parentNode) {
     itemSetFrame.parentNode.removeChild(itemSetFrame);
diff --git a/src/timeline/component/GroupSet.js b/src/timeline/component/GroupSet.js
index cc439c94..f57a7e23 100644
--- a/src/timeline/component/GroupSet.js
+++ b/src/timeline/component/GroupSet.js
@@ -2,16 +2,22 @@
  * An GroupSet holds a set of groups
  * @param {Panel} contentPanel      Panel where the ItemSets will be created
  * @param {Panel} labelPanel        Panel where the labels will be created
+ * @param {Panel} backgroundPanel   Panel where the vertical lines of box
+ *                                  items are created
+ * @param {Panel} axisPanel         Panel on the axis where the dots of box
+ *                                  items will be created
  * @param {Object} [options]        See GroupSet.setOptions for the available
  *                                  options.
  * @constructor GroupSet
  * @extends Panel
  */
-function GroupSet(contentPanel, labelPanel, options) {
+function GroupSet(contentPanel, labelPanel, backgroundPanel, axisPanel, options) {
   this.id = util.randomUUID();
 
   this.contentPanel = contentPanel;
   this.labelPanel = labelPanel;
+  this.backgroundPanel = backgroundPanel;
+  this.axisPanel = axisPanel;
   this.options = options || {};
 
   this.range = null;      // Range or Object {start: number, end: number}
@@ -64,7 +70,7 @@ GroupSet.prototype._create = function _create () {
   this.frame = frame;
 
   this.labelSet = new Panel({
-    className: 'labelSet',
+    className: 'labelset',
     width: '100%',
     height: '100%'
   });
@@ -272,11 +278,12 @@ GroupSet.prototype.repaint = function repaint() {
 
             // TODO: do not recreate the group with every update
 
-            group = new Group(me.frame, me.labelSet.frame, id, groupOptions);
+            group = new Group(me, me.labelSet, me.backgroundPanel, me.axisPanel, id, groupOptions);
             group.on('change', me.emit.bind(me, 'change')); // propagate change event
             group.setRange(me.range);
             group.setItems(me.itemsData); // attach items data
             groups[id] = group;
+            group.parent = me;
 
             // Note: it is important to add the binding after group.setItems
             // is executed, because that will start an infinite loop
@@ -323,7 +330,6 @@ GroupSet.prototype.repaint = function repaint() {
 
   // reposition the labels and calculate the maximum label width
   // TODO: labels are not displayed correctly when orientation=='top'
-  // TODO: width of labelPanel is not immediately updated on a change in groups
   var maxWidth = 0;
   for (id in groups) {
     if (groups.hasOwnProperty(id)) {
@@ -333,19 +339,19 @@ GroupSet.prototype.repaint = function repaint() {
   }
   resized = util.updateProperty(this.props.labels, 'width', maxWidth) || resized;
 
-  // recalculate the height of the groupset
+  // recalculate the height of the groupset, and recalculate top positions of the groups
   var fixedHeight = (asSize(options.height) != null);
   var height;
   if (!fixedHeight) {
     // height is not specified, calculate the sum of the height of all groups
     height = 0;
 
-    for (id in this.groups) {
-      if (this.groups.hasOwnProperty(id)) {
-        group = this.groups[id];
-        height += group.height;
-      }
-    }
+    this.groupIds.forEach(function (id) {
+      var group = groups[id];
+      group.top = height;
+      if (group.itemSet) group.itemSet.top = group.top; // TODO: this is an ugly hack
+      height += group.height;
+    });
   }
 
   // update classname
@@ -385,7 +391,6 @@ GroupSet.prototype.hide = function hide() {
 
 /**
  * Show the component in the DOM (when not already visible).
- * A repaint will be executed when the component is not visible
  * @return {Boolean} changed
  */
 GroupSet.prototype.show = function show() {
diff --git a/src/timeline/component/ItemSet.js b/src/timeline/component/ItemSet.js
index d44a2527..cdb4466a 100644
--- a/src/timeline/component/ItemSet.js
+++ b/src/timeline/component/ItemSet.js
@@ -2,17 +2,22 @@
  * An ItemSet holds a set of items and ranges which can be displayed in a
  * range. The width is determined by the parent of the ItemSet, and the height
  * is determined by the size of the items.
- * @param {Object} [options]        See ItemSet.setOptions for the available
- *                                  options.
+ * @param {Panel} backgroundPanel Panel which can be used to display the
+ *                                vertical lines of box items.
+ * @param {Panel} axisPanel       Panel on the axis where the dots of box-items
+ *                                can be displayed.
+ * @param {Object} [options]      See ItemSet.setOptions for the available options.
  * @constructor ItemSet
  * @extends Panel
  */
 // TODO: improve performance by replacing all Array.forEach with a for loop
-function ItemSet(options) {
+function ItemSet(backgroundPanel, axisPanel, options) {
   this.id = util.randomUUID();
 
   // one options object is shared by this itemset and all its items
   this.options = options || {};
+  this.backgroundPanel = backgroundPanel;
+  this.axisPanel = axisPanel;
   this.itemOptions = Object.create(this.options);
   this.dom = {};
   this.hammer = null;
@@ -76,7 +81,7 @@ ItemSet.prototype._create = function _create(){
   // create background panel
   var background = document.createElement('div');
   background.className = 'background';
-  frame.appendChild(background);
+  this.backgroundPanel.frame.appendChild(background);
   this.dom.background = background;
 
   // create foreground panel
@@ -89,7 +94,7 @@ ItemSet.prototype._create = function _create(){
   var axis = document.createElement('div');
   axis.className = 'axis';
   this.dom.axis = axis;
-  frame.appendChild(axis);
+  this.axisPanel.frame.appendChild(axis);
 
   // attach event listeners
   // TODO: use event listeners from the rootpanel to improve performance
@@ -131,6 +136,37 @@ ItemSet.prototype._create = function _create(){
  */
 ItemSet.prototype.setOptions = Component.prototype.setOptions;
 
+/**
+ * Hide the component from the DOM
+ */
+ItemSet.prototype.hide = function hide() {
+  // remove the axis with dots
+  if (this.dom.axis.parentNode) {
+    this.dom.axis.parentNode.removeChild(this.dom.axis);
+  }
+
+  // remove the background with vertical lines
+  if (this.dom.background.parentNode) {
+    this.dom.background.parentNode.removeChild(this.dom.background);
+  }
+};
+
+/**
+ * Show the component in the DOM (when not already visible).
+ * @return {Boolean} changed
+ */
+ItemSet.prototype.show = function show() {
+  // show axis with dots
+  if (!this.dom.axis.parentNode) {
+    this.axisPanel.frame.appendChild(this.dom.axis);
+  }
+
+  // show background with vertical lines
+  if (!this.dom.background.parentNode) {
+    this.backgroundPanel.frame.appendChild(this.dom.background);
+  }
+};
+
 /**
  * Set range (start and end).
  * @param {Range | Object} range  A Range or an object containing start and end.
diff --git a/src/timeline/component/Panel.js b/src/timeline/component/Panel.js
index 4b7378a4..84d70e7b 100644
--- a/src/timeline/component/Panel.js
+++ b/src/timeline/component/Panel.js
@@ -76,7 +76,14 @@ Panel.prototype.insertBefore = function (child, beforeChild) {
       if (frame.parentNode) {
         frame.parentNode.removeChild(frame);
       }
-      this.frame.appendChild(frame);
+
+      var beforeFrame = beforeChild.getFrame();
+      if (beforeFrame) {
+        this.frame.insertBefore(frame, beforeFrame);
+      }
+      else {
+        this.frame.appendChild(frame);
+      }
     }
   }
 };
diff --git a/src/timeline/component/TimeAxis.js b/src/timeline/component/TimeAxis.js
index 95f71057..feaf074c 100644
--- a/src/timeline/component/TimeAxis.js
+++ b/src/timeline/component/TimeAxis.js
@@ -86,7 +86,7 @@ TimeAxis.prototype.repaint = function () {
       frame = this.frame;
 
   // update classname
-  frame.className = 'axis'; // TODO: add className from options if defined
+  frame.className = 'timeaxis'; // TODO: add className from options if defined
 
   var parent = frame.parentNode;
   if (parent) {
@@ -114,6 +114,7 @@ TimeAxis.prototype.repaint = function () {
     var beforeChild = frame.nextSibling;
     parent.removeChild(frame);
 
+    // TODO: top/bottom positioning should be determined by options set in the Timeline, not here
     if (orientation == 'top') {
       frame.style.top = '0';
       frame.style.left = '0';
diff --git a/src/timeline/component/css/groupset.css b/src/timeline/component/css/groupset.css
index cf0dafb0..2d03ae87 100644
--- a/src/timeline/component/css/groupset.css
+++ b/src/timeline/component/css/groupset.css
@@ -1,6 +1,6 @@
 
 /* TODO: cleanup
-.vis.timeline .groupSet {
+.vis.timeline .groupset {
   position: relative;
   padding: 0;
   margin: 0;
@@ -18,7 +18,7 @@
 }
 */
 
-.vis.timeline .labelSet {
+.vis.timeline .labelset {
   position: relative;
   width: 100%;
 
@@ -28,7 +28,7 @@
   box-sizing: border-box;
 }
 
-.vis.timeline .labelSet .vlabel {
+.vis.timeline .labelset .vlabel {
   position: relative;
   left: 0;
   top: 0;
@@ -39,21 +39,21 @@
   box-sizing: border-box;
 }
 
-.vis.timeline.bottom .labelSet .vlabel,
+.vis.timeline.bottom .labelset .vlabel,
 .vis.timeline.top .vpanel.side-content,
-.vis.timeline.top .itemset .axis {
+.vis.timeline.top .groupset .itemset {
   border-top: 1px solid #bfbfbf;
   border-bottom: none;
 }
 
-.vis.timeline.top .labelSet .vlabel,
+.vis.timeline.top .labelset .vlabel,
 .vis.timeline.bottom .vpanel.side-content,
-.vis.timeline.bottom .itemset .axis {
+.vis.timeline.bottom .groupset .itemset {
   border-top: none;
   border-bottom: 1px solid #bfbfbf;
 }
 
-.vis.timeline .labelSet .vlabel .inner {
+.vis.timeline .labelset .vlabel .inner {
   display: inline-block;
   padding: 5px;
 }
diff --git a/src/timeline/component/css/item.css b/src/timeline/component/css/item.css
index 08c959b4..5d176738 100644
--- a/src/timeline/component/css/item.css
+++ b/src/timeline/component/css/item.css
@@ -90,6 +90,8 @@
 
   -webkit-transition: height .4s ease-in-out;
   transition:         height .4s ease-in-out;
+
+  color: red;
 }
 
 .vis.timeline .item .content {
diff --git a/src/timeline/component/css/itemset.css b/src/timeline/component/css/itemset.css
index 52a76f81..4d21c747 100644
--- a/src/timeline/component/css/itemset.css
+++ b/src/timeline/component/css/itemset.css
@@ -4,6 +4,9 @@
   padding: 0;
   margin: 0;
 
+  -moz-box-sizing: border-box;
+  box-sizing: border-box;
+
   /* FIXME: get transoition working for rootpanel and itemset
   -webkit-transition: height 4s ease-in-out;
   transition:         height 4s ease-in-out;
@@ -17,5 +20,5 @@
 }
 
 .vis.timeline .axis {
-  position: absolute;
+  overflow: visible;
 }
diff --git a/src/timeline/component/css/timeaxis.css b/src/timeline/component/css/timeaxis.css
index dd02204a..38f8ccb9 100644
--- a/src/timeline/component/css/timeaxis.css
+++ b/src/timeline/component/css/timeaxis.css
@@ -1,15 +1,15 @@
-.vis.timeline .axis {
+.vis.timeline .timeaxis {
   position: absolute;
 }
 
-.vis.timeline .axis .text {
+.vis.timeline .timeaxis .text {
   position: absolute;
   color: #4d4d4d;
   padding: 3px;
   white-space: nowrap;
 }
 
-.vis.timeline .axis .text.measure {
+.vis.timeline .timeaxis .text.measure {
   position: absolute;
   padding-left: 0;
   padding-right: 0;
@@ -18,13 +18,13 @@
   visibility: hidden;
 }
 
-.vis.timeline .axis .grid.vertical {
+.vis.timeline .timeaxis .grid.vertical {
   position: absolute;
   width: 0;
   border-right: 1px solid;
 }
 
-.vis.timeline .axis .grid.horizontal {
+.vis.timeline .timeaxis .grid.horizontal {
   position: absolute;
   left: 0;
   width: 100%;
@@ -32,10 +32,10 @@
   border-bottom: 1px solid;
 }
 
-.vis.timeline .axis .grid.minor {
+.vis.timeline .timeaxis .grid.minor {
   border-color: #e5e5e5;
 }
 
-.vis.timeline .axis .grid.major {
+.vis.timeline .timeaxis .grid.major {
   border-color: #bfbfbf;
 }
diff --git a/src/timeline/component/item/ItemBox.js b/src/timeline/component/item/ItemBox.js
index ff87f7e9..05aa8ffb 100644
--- a/src/timeline/component/item/ItemBox.js
+++ b/src/timeline/component/item/ItemBox.js
@@ -39,9 +39,8 @@ ItemBox.prototype = new Item (null, null);
  */
 ItemBox.prototype.isVisible = function isVisible (range) {
   // determine visibility
-  // TODO: account for the width of the item. Right now we add 1/4 to the window
+  // TODO: account for the real width of the item. Right now we just add 1/4 to the window
   var interval = (range.end - range.start) / 4;
-  interval = 0; // TODO: remove
   return (this.data.start > range.start - interval) && (this.data.start < range.end + interval);
 };
 
@@ -215,17 +214,17 @@ ItemBox.prototype.repositionY = function repositionY () {
     box.style.top = (this.top || 0) + 'px';
     box.style.bottom = '';
 
-    line.style.top = '0px';
+    line.style.top = '0';
     line.style.bottom = '';
-    line.style.height = this.top + 'px';
+    line.style.height = (this.parent.top + this.top + 1) + 'px';
   }
   else { // orientation 'bottom'
     box.style.top = '';
     box.style.bottom = (this.top || 0) + 'px';
 
-    line.style.top = '';
-    line.style.bottom = '0px';
-    line.style.height = this.top + 'px';
+    line.style.top = (this.parent.top + this.parent.height - this.top - 1) + 'px';
+    line.style.bottom = '0';
+    line.style.height = '';
   }
 
   dot.style.top = (-this.props.dot.height / 2) + 'px';
diff --git a/test/timeline.html b/test/timeline.html
index 81fae4e2..2c842cdf 100644
--- a/test/timeline.html
+++ b/test/timeline.html
@@ -35,6 +35,19 @@
     });
   };
 </script>
+
+<div>
+  <label for="currenttime"><input id="currenttime" type="checkbox" checked="true"> Show current time</label>
+</div>
+<script>
+  var currenttime = document.getElementById('currenttime');
+  currenttime.onchange = function () {
+    timeline.setOptions({
+      showCurrentTime: currenttime.checked
+    });
+  };
+</script>
+
 <br>
 
 <div id="visualization"></div>