diff -r 000000000000 -r 6474c204b198 browser/components/tabview/test/browser_tabview_layout.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/tabview/test/browser_tabview_layout.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,111 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function test() {
+  waitForExplicitFinish();
+
+  // verify initial state
+  ok(!TabView.isVisible(), "Tab View starts hidden");
+
+  window.addEventListener("tabviewshown", onTabViewWindowLoaded, false);
+  TabView.toggle();
+}
+
+let originalGroupItem = null;
+let originalTab = null;
+let contentWindow = null;
+
+function onTabViewWindowLoaded() {
+  window.removeEventListener("tabviewshown", onTabViewWindowLoaded, false);
+  ok(TabView.isVisible(), "Tab View is visible");
+
+  contentWindow = document.getElementById("tab-view").contentWindow;
+
+  is(contentWindow.GroupItems.groupItems.length, 1, "There is one group item on startup");
+  originalGroupItem = contentWindow.GroupItems.groupItems[0];
+  is(originalGroupItem.getChildren().length, 1, "There should be one Tab Item in that group.");
+  contentWindow.UI.setActive(originalGroupItem);
+
+  [originalTab] = gBrowser.visibleTabs;
+
+  testEmptyGroupItem(contentWindow);
+}
+
+function testEmptyGroupItem(contentWindow) {
+  let groupItemCount = contentWindow.GroupItems.groupItems.length;
+
+  // Preparation
+  //
+    
+  // create empty group item
+  let emptyGroupItem = createEmptyGroupItem(contentWindow, 253, 335, 100);
+  ok(emptyGroupItem.isEmpty(), "This group is empty");
+
+  is(contentWindow.GroupItems.groupItems.length, ++groupItemCount,
+     "The number of groups is increased by 1");
+
+  // add four blank items
+  contentWindow.UI.setActive(emptyGroupItem);
+
+  let numNewTabs = 4;
+  let items = [];
+  for(let t=0; t<numNewTabs; t++) {
+    let newItem = contentWindow.gBrowser.loadOneTab("about:blank")._tabViewTabItem;
+    ok(newItem.container, "Created element "+t+":"+newItem.container);
+    items.push(newItem);
+  }
+
+  // Define main test function
+  //
+
+  let mainTestFunc = function() {
+    for(let j=0; j<numNewTabs; j++) {
+      for(let i=0; i<numNewTabs; i++) {
+        if (j!=i) {
+          // make sure there is no overlap between j's title and i's box.
+          let jitem = items[j];
+          let iitem = items[i];
+          let $jtitle = contentWindow.iQ(jitem.container).find(".tab-title");
+          let jbounds = $jtitle.bounds();
+          let ibounds = contentWindow.iQ(iitem.container).bounds();
+
+          ok(
+            (jbounds.top+jbounds.height < ibounds.top) || 
+            (jbounds.top > ibounds.top + ibounds.height) ||
+            (jbounds.left+jbounds.width < ibounds.left) || 
+            (jbounds.left > ibounds.left + ibounds.width),
+            "Items do not overlap: "
+            +jbounds.left+","+jbounds.top+","+jbounds.width+","+jbounds.height+" ; "
+            +ibounds.left+","+ibounds.top+","+ibounds.width+","+ibounds.height);        
+        }
+      }
+    }
+
+    // Shut down
+    emptyGroupItem.addSubscriber("close", function onClose() {
+      emptyGroupItem.removeSubscriber("close", onClose);
+  
+      // check the number of groups.
+      is(contentWindow.GroupItems.groupItems.length, --groupItemCount,
+         "The number of groups is decreased by 1");
+
+      let onTabViewHidden = function() {
+        window.removeEventListener("tabviewhidden", onTabViewHidden, false);
+        // assert that we're no longer in tab view
+        ok(!TabView.isVisible(), "Tab View is hidden");
+        finish();
+      };
+      window.addEventListener("tabviewhidden", onTabViewHidden, false);
+  
+      TabView.toggle();
+    });
+  
+    let closeButton = emptyGroupItem.container.getElementsByClassName("close");
+    ok(closeButton[0], "Group close button exists");
+  
+    // click the close button
+    EventUtils.synthesizeMouse(closeButton[0], 1, 1, {}, contentWindow);
+  };
+
+  mainTestFunc();
+}