add tooltip for token under the mouse

helps building modes and themes

kitchen-sink.html

@@ -235,6 +235,14 @@
         <input type="checkbox" id="fade_fold_widgets">
       </td>
     </tr>
+    <tr>
+      <td >
+        <label for="highlight_token">Show token info</label>
+      </td>
+      <td>
+        <input type="checkbox" id="highlight_token">
+      </td>
+    </tr>
   </table>
   </td></tr>
   </table>