Fixes a bug in Tree where a null pointer exception can occur if a click event propagates to the root TreeItem, which can happen in IE6.  We now check that the target item is not the root TreeItem.

Patch by: jlabanca
Review by: TBR (rajeev)
 


git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/1.5@3391 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/src/com/google/gwt/user/client/ui/Tree.java b/user/src/com/google/gwt/user/client/ui/Tree.java
index 334f166..7d92b6d 100644
--- a/user/src/com/google/gwt/user/client/ui/Tree.java
+++ b/user/src/com/google/gwt/user/client/ui/Tree.java
@@ -797,7 +797,7 @@
     collectElementChain(chain, getElement(), hElem);
 
     TreeItem item = findItemByChain(chain, 0, root);
-    if (item != null) {
+    if (item != null && item != root) {
       if (item.getChildCount() > 0
           && DOM.isOrHasChild(item.getImageElement(), hElem)) {
         item.setState(!item.getState(), true);
@@ -993,8 +993,6 @@
 
   /**
    * Move the tree focus to the specified selected item.
-   * 
-   * @param
    */
   private void moveFocus() {
     HasFocus focusableWidget = curSelection.getFocusableWidget();