diff --git a/accessible/src/xul/nsXULTreeAccessible.cpp b/accessible/src/xul/nsXULTreeAccessible.cpp
index 057a77325f0..6e8fc3c21cf 100644
--- a/accessible/src/xul/nsXULTreeAccessible.cpp
+++ b/accessible/src/xul/nsXULTreeAccessible.cpp
@@ -92,12 +92,16 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(nsXULTreeAccessible)
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(nsXULTreeAccessible,
                                                   nsAccessible)
-CycleCollectorTraverseCache(tmp->mAccessibleCache, &cb);
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mTree)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mTreeView)
+  CycleCollectorTraverseCache(tmp->mAccessibleCache, &cb);
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(nsXULTreeAccessible,
                                                 nsAccessible)
-ClearCache(tmp->mAccessibleCache);
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mTree)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mTreeView)
+  ClearCache(tmp->mAccessibleCache);
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(nsXULTreeAccessible)
diff --git a/accessible/tests/mochitest/actions/test_tree.xul b/accessible/tests/mochitest/actions/test_tree.xul
index fe4921abfef..94c46f4da13 100644
--- a/accessible/tests/mochitest/actions/test_tree.xul
+++ b/accessible/tests/mochitest/actions/test_tree.xul
@@ -43,7 +43,7 @@
     // gA11yEventDumpID = "debug";
     //gA11yEventDumpToConsole = true; // debug
 
-    function doTestActions()
+    function doTest()
     {
       var treeNode = getNode("tree");
 
@@ -91,15 +91,8 @@
       testActions(actions); // Will call SimpleTest.finish();
     }
 
-    function doTest()
-    {
-      var treeNode = getNode("tree");
-      waitForEvent(EVENT_REORDER, treeNode, doTestActions);
-      treeNode.view = new nsTreeTreeView();
-    }
-
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTreeTreeView());
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/attributes/test_obj_group_tree.xul b/accessible/tests/mochitest/attributes/test_obj_group_tree.xul
index 1b6ecef7f68..6b8461ef7f3 100644
--- a/accessible/tests/mochitest/attributes/test_obj_group_tree.xul
+++ b/accessible/tests/mochitest/attributes/test_obj_group_tree.xul
@@ -24,7 +24,7 @@
     ////////////////////////////////////////////////////////////////////////////
     // Test
 
-    function doTestAttrs()
+    function doTest()
     {
       var treeNode = getNode("tree");
 
@@ -50,15 +50,8 @@
       SimpleTest.finish();
     }
 
-    function doTest()
-    {
-      var treeNode = getNode("tree");
-      waitForEvent(EVENT_REORDER, treeNode, doTestAttrs);
-      treeNode.view = new nsTreeTreeView();
-    }
-
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTreeTreeView());
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/events/test_focus_tree.xul b/accessible/tests/mochitest/events/test_focus_tree.xul
index 16200adc645..f956de4fc5d 100644
--- a/accessible/tests/mochitest/events/test_focus_tree.xul
+++ b/accessible/tests/mochitest/events/test_focus_tree.xul
@@ -29,23 +29,6 @@
     ////////////////////////////////////////////////////////////////////////////
     // Invokers
 
-    function setTreeView(aTreeID, aView)
-    {
-      this.DOMNode = getNode(aTreeID);
-
-      this.eventSeq = [
-        new invokerChecker(EVENT_REORDER, this.DOMNode)
-      ];
-
-      this.invoke = function setTreeView_invoke()
-      {
-        this.DOMNode.treeBoxObject.view = aView;
-      }
-
-      this.getID = function setTreeView_getID()
-        { return "set tree view for " + prettyName(aTreeID); }
-    };
-
     function focusTree(aTreeID)
     {
       var checker = new focusChecker(getFirstTreeItem, aTreeID);
@@ -82,7 +65,6 @@
     {
       gQueue = new eventQueue();
 
-      gQueue.push(new setTreeView("tree", new nsTableTreeView(5)));
       gQueue.push(new focusTree("tree"));
       gQueue.push(new moveToNextItem("tree"));
       gQueue.push(new synthFocus("emptytree"));
@@ -94,7 +76,7 @@
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTableTreeView(5));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/focus/test_takeFocus.xul b/accessible/tests/mochitest/focus/test_takeFocus.xul
index 7f4c42d6013..50858ce9b2d 100644
--- a/accessible/tests/mochitest/focus/test_takeFocus.xul
+++ b/accessible/tests/mochitest/focus/test_takeFocus.xul
@@ -26,23 +26,6 @@
     ////////////////////////////////////////////////////////////////////////////
     // Invokers
 
-    function setTreeView(aTreeID, aView)
-    {
-      this.DOMNode = getNode(aTreeID);
-
-      this.eventSeq = [
-        new invokerChecker(EVENT_REORDER, this.DOMNode)
-      ];
-
-      this.invoke = function setTreeView_invoke()
-      {
-        this.DOMNode.treeBoxObject.view = aView;
-      }
-
-      this.getID = function setTreeView_getID()
-        { return "set tree view for " + prettyName(aTreeID); }
-    };
-
     function takeFocusInvoker(aID, aArgConverterFunc)
     {
       this.targetFunc = aArgConverterFunc ? aArgConverterFunc : getAccessible;
@@ -77,7 +60,6 @@
       // Test focus events.
       gQueue = new eventQueue();
 
-      gQueue.push(new setTreeView("tree", new nsTableTreeView(5)));
       gQueue.push(new takeFocusInvoker("tree", getLastChild));
       gQueue.push(new takeFocusInvoker("listitem2"));
 
@@ -85,7 +67,7 @@
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTests);
+    addA11yXULTreeLoadEvent(doTests, "tree", new nsTableTreeView(5));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/hittest/test_general.xul b/accessible/tests/mochitest/hittest/test_general.xul
index ae9621078e9..cdb91a70b56 100644
--- a/accessible/tests/mochitest/hittest/test_general.xul
+++ b/accessible/tests/mochitest/hittest/test_general.xul
@@ -14,6 +14,8 @@
 
   <script type="application/javascript"
           src="../common.js" />
+  <script type="application/javascript"
+          src="../events.js" />
   <script type="application/javascript"
           src="../layout.js" />
 
@@ -21,26 +23,13 @@
   <![CDATA[
     function doTest()
     {
-      // Initialize the tree
-      var view = new nsTableTreeView(5);
-
-      var tree = getNode("tree");
-      var treeBox = tree.treeBoxObject;
-      treeBox.view = view;
-
-      // Tests
-      var treecols = getNode("treecols");
-      var x = treecols.boxObject.x;
-      var y = treecols.boxObject.y;
-
-      testChildAtPoint(tree, x, y, false, treecols);
-      testChildAtPoint(tree, x, y, true, "col1");
+      hitTest("tree", "treecols", "col1");
 
       SimpleTest.finish();
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTableTreeView(5));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/relations/test_tree.xul b/accessible/tests/mochitest/relations/test_tree.xul
index 6f888776b33..7a74aaeb56c 100644
--- a/accessible/tests/mochitest/relations/test_tree.xul
+++ b/accessible/tests/mochitest/relations/test_tree.xul
@@ -24,7 +24,7 @@
     ////////////////////////////////////////////////////////////////////////////
     // Test
 
-    function doTestRelations()
+    function doTest()
     {
       var treeNode = getNode("tree");
 
@@ -54,15 +54,8 @@
       SimpleTest.finish();
     }
 
-    function doTest()
-    {
-      var treeNode = getNode("tree");
-      waitForEvent(EVENT_REORDER, treeNode, doTestRelations);
-      treeNode.view = new nsTreeTreeView();
-    }
-
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTreeTreeView());
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/table/test_headers_tree.xul b/accessible/tests/mochitest/table/test_headers_tree.xul
index d4add49e09b..9b69e8a0d75 100644
--- a/accessible/tests/mochitest/table/test_headers_tree.xul
+++ b/accessible/tests/mochitest/table/test_headers_tree.xul
@@ -24,26 +24,11 @@
     ////////////////////////////////////////////////////////////////////////////
     // Test
 
-    var gTree = null;
-    var gTreeBox = null;
-    var gTreeView = null;
-
     // gA11yEventDumpID = "debug";
 
     function doTest()
     {
-      // Initialize the tree
-      gTree = document.getElementById("tree");
-      gTreeBox = gTree.treeBoxObject;
-      gView = new nsTableTreeView(3);
-
-      waitForEvent(EVENT_REORDER, gTree, continueTest);
-      gTreeBox.view = gView;
-    }
-
-    function continueTest()
-    {
-      var treeAcc = getAccessible(gTree, [nsIAccessibleTable]);
+      var treeAcc = getAccessible("tree", [nsIAccessibleTable]);
 
       var headerInfoMap = [
         {
@@ -84,7 +69,7 @@
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTableTreeView(3));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/table/test_indexes_tree.xul b/accessible/tests/mochitest/table/test_indexes_tree.xul
index c61e9a2a0ab..89a751419bc 100644
--- a/accessible/tests/mochitest/table/test_indexes_tree.xul
+++ b/accessible/tests/mochitest/table/test_indexes_tree.xul
@@ -24,37 +24,22 @@
     ////////////////////////////////////////////////////////////////////////////
     // Test
 
-    var gTree = null;
-    var gTreeBox = null;
-    var gTreeView = null;
-
     // gA11yEventDumpID = "debug";
 
     function doTest()
-    {
-      // Initialize the tree
-      gTree = document.getElementById("tree");
-      gTreeBox = gTree.treeBoxObject;
-      gView = new nsTableTreeView(3);
-
-      waitForEvent(EVENT_REORDER, gTree, continueTest);
-      gTreeBox.view = gView;
-    }
-
-    function continueTest()
     {
       var idxes = [
         [0, 1],
         [2, 3],
         [4, 5]
       ];
-      testTableIndexes(gTree, idxes);
+      testTableIndexes("tree", idxes);
 
       SimpleTest.finish();
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTableTreeView(3));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/table/test_sels_tree.xul b/accessible/tests/mochitest/table/test_sels_tree.xul
index f73fd03cd5d..0e1d0ad0eb9 100644
--- a/accessible/tests/mochitest/table/test_sels_tree.xul
+++ b/accessible/tests/mochitest/table/test_sels_tree.xul
@@ -26,24 +26,9 @@
     ////////////////////////////////////////////////////////////////////////////
     // Test
 
-    var gTree = null;
-    var gTreeBox = null;
-    var gTreeView = null;
-
     // gA11yEventDumpID = "debug";
 
     function doTest()
-    {
-      // Initialize the tree
-      gTree = document.getElementById("tree");
-      gTreeBox = gTree.treeBoxObject;
-      gView = new nsTableTreeView(3);
-
-      waitForEvent(EVENT_REORDER, gTree, continueTest);
-      gTreeBox.view = gView;
-    }
-
-    function continueTest()
     {
       var cellsArray =
       [
@@ -52,15 +37,15 @@
         [false, false]
       ];
 
-      testTableSelection(gTree, cellsArray);
-      testSelectTableRow(gTree, 0, cellsArray);
-      testUnselectTableRow(gTree, 0, cellsArray);
+      testTableSelection("tree", cellsArray);
+      testSelectTableRow("tree", 0, cellsArray);
+      testUnselectTableRow("tree", 0, cellsArray);
 
       SimpleTest.finish();
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "tree", new nsTableTreeView(3));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/table/test_struct_tree.xul b/accessible/tests/mochitest/table/test_struct_tree.xul
index b06ca53268b..2037bf7149c 100644
--- a/accessible/tests/mochitest/table/test_struct_tree.xul
+++ b/accessible/tests/mochitest/table/test_struct_tree.xul
@@ -26,24 +26,9 @@
     ////////////////////////////////////////////////////////////////////////////
     // Test
 
-    var gTree = null;
-    var gTreeBox = null;
-    var gTreeView = null;
-
     // gA11yEventDumpID = "debug";
 
     function doTest()
-    {
-      // Initialize the tree
-      gTree = document.getElementById("table");
-      gTreeBox = gTree.treeBoxObject;
-      gView = new nsTableTreeView(3);
-
-      waitForEvent(EVENT_REORDER, gTree, continueTest);
-      gTreeBox.view = gView;
-    }
-
-    function continueTest()
     {
       var cellsArray = [
         [kDataCell, kDataCell],
@@ -51,13 +36,13 @@
         [kDataCell, kDataCell]
       ];
 
-      testTableStruct(gTree, cellsArray, kTreeColumnHeader);
+      testTableStruct("table", cellsArray, kTreeColumnHeader);
 
       SimpleTest.finish();
     }
 
     SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
+    addA11yXULTreeLoadEvent(doTest, "table", new nsTableTreeView(3));
   ]]>
   </script>
 
diff --git a/accessible/tests/mochitest/treeview.js b/accessible/tests/mochitest/treeview.js
index 874be9ad6eb..4971059534b 100644
--- a/accessible/tests/mochitest/treeview.js
+++ b/accessible/tests/mochitest/treeview.js
@@ -1,3 +1,44 @@
+/**
+ * Helper method to start a single XUL tree test.
+ */
+var gXULTreeLoadQueue = null;
+function addA11yXULTreeLoadEvent(aDoTestFunc, aTreeID, aTreeView)
+{
+  function loadXULTree(aTreeID, aTreeView)
+  {
+    this.treeNode = getNode(aTreeID);
+
+    this.eventSeq = [
+      new invokerChecker(EVENT_REORDER, this.treeNode)
+    ];
+
+    this.invoke = function loadXULTree_invoke()
+    {
+      this.treeNode.treeBoxObject.view = aTreeView;
+    }
+
+    this.getID = function loadXULTree_getID()
+    {
+      return "Load XUL tree " + prettyName(aTreeID);
+    }
+  }
+
+  function doXULTreeTest()
+  {
+    gXULTreeLoadQueue = new eventQueue();
+    gXULTreeLoadQueue.push(new loadXULTree(aTreeID, aTreeView));
+    gXULTreeLoadQueue.onFinish = function()
+    {
+      SimpleTest.executeSoon(aDoTestFunc);
+      return DO_NOT_FINISH_TEST;
+    }
+    gXULTreeLoadQueue.invoke();
+  }
+
+  addA11yLoadEvent(doXULTreeTest);
+}
+
+
 function nsTableTreeView(aRowCount)
 {
   this.__proto__ = new nsTreeView();