implement api level toggling
 and rename navtree.js to android-developer-reference.js for all reference related scripts
 TODO: shading for hidden classes in the treeview navigation... these aren't dynamic yet.
diff --git a/tools/droiddoc/templates-sdk/customization.cs b/tools/droiddoc/templates-sdk/customization.cs
index 79fc282..6bdb992 100644
--- a/tools/droiddoc/templates-sdk/customization.cs
+++ b/tools/droiddoc/templates-sdk/customization.cs
@@ -47,34 +47,51 @@
       <div id="headerRight">
           <div id="headerLinks">
           <?cs if:template.showLanguageMenu ?>
-              <img src="<?cs var:toroot ?>assets/images/icon_world.jpg" alt="" /> 
-              <span id="language">
+            <img src="<?cs var:toroot ?>assets/images/icon_world.jpg" alt="Language:" /> 
+            <span id="language">
              	<select name="language" onChange="changeLangPref(this.value, true)">
-    			<option value="en">English&nbsp;&nbsp;&nbsp;</option>
-    			<option value="ja">日本語</option>
-    			<?cs # 
-			<option value="de">Deutsch</option> 
-    			<option value="es">Español</option>
-    			<option value="fr">Français</option>
-    			<option value="it">Italiano</option>
-    			<option value="zh-CN">中文 (简体)</option>
-    			<option value="zh-TW">中文 (繁體)</option>
-			?>
+          			<option value="en">English&nbsp;&nbsp;&nbsp;</option>
+          			<option value="ja">日本語</option>
+          			<?cs # 
+      			    <option value="de">Deutsch</option> 
+          			<option value="es">Español</option>
+          			<option value="fr">Français</option>
+          			<option value="it">Italiano</option>
+          			<option value="zh-CN">中文 (简体)</option>
+          			<option value="zh-TW">中文 (繁體)</option>
+      			    ?>
              	</select>	
              	<script type="text/javascript">
              	  <!--  
                   loadLangPref();  
              	   //-->
              	</script>
-             </span>
+            </span>
           <?cs /if ?>
           <a href="http://www.android.com">Android.com</a>
           </div><?cs 
-          call:default_search_box() ?>
+          call:default_search_box() ?><?cs 
+    	 	  if:reference ?>
+    			  <div id="api-level-toggle">
+    			    <label for="apiLevelControl"><a href="<?cs var:toroot ?>guide/appendix/api-levels.html">Filter by API Level</a>: </label>
+    			    <select id="apiLevelControl">
+    			      <!-- option elements added by buildApiLevelToggle() -->
+    			    </select>
+    			  </div>
+    	 	    <script>
+              var SINCE_DATA = [ <?cs 
+                each:since = since ?>'<?cs 
+                  var:since.name ?>'<?cs 
+                  if:!last(since) ?>, <?cs /if ?><?cs
+                /each 
+              ?> ];
+              buildApiLevelToggle();
+            </script><?cs 
+    			/if ?>
       </div><!-- headerRight -->
       <script type="text/javascript">
         <!--  
-        changeTabLang(getLangPref());  
+        changeTabLang(getLangPref());
         //-->
       </script>
   </div><!-- header --><?cs