wip-lk
diff --git a/bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/navigator/NavigatorContentHandler.java b/bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/navigator/NavigatorContentHandler.java
index b8a525a..955e6bd 100644
--- a/bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/navigator/NavigatorContentHandler.java
+++ b/bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/navigator/NavigatorContentHandler.java
@@ -50,6 +50,7 @@
 	return null;
 }
 public INavigatorContentProvider createContentProvider(NavigatorContentDescriptor descriptor) {
+	if (descriptor == null) return null;
 	INavigatorContentProvider contentProvider = (INavigatorContentProvider)contentProviders.get(descriptor.getId());
 	if  (contentProvider != null) return contentProvider;
 	try {
diff --git a/bundles/org.eclipse.ui/schema/navigator.exsd b/bundles/org.eclipse.ui/schema/navigator.exsd
index 4634e00..f2a2588 100644
--- a/bundles/org.eclipse.ui/schema/navigator.exsd
+++ b/bundles/org.eclipse.ui/schema/navigator.exsd
@@ -231,10 +231,10 @@
          <attribute name="elementClass" type="string" use="required">

             <annotation>

                <documentation>

-                  

+                  The element class of the root elements.

                </documentation>

                <appInfo>

-                  <meta.attribute kind="java" basedOn=""/>

+                  <meta.attribute kind="java"/>

                </appInfo>

             </annotation>

          </attribute>