two of my Graphical Layout components are missing
<p>I've recently started Eclipse and Android programming and I notices that alot of my Visual Components are missing their classes. </p>

<p>Such as the Sliding Tab (which I need for my UI) which only gives me this message when placed:</p>

<blockquote>
  <p>error! ClassCastException:
  com.android.layoutlib.bridge.MockView
  cannot be cast to
  android.view.ViewGroup Exception
  details are logged in Window > Show
  View > Error LogThe following classes
  could not be found:
  - SlidingDrawer</p>
</blockquote>

<p>And with the Tabhost &amp; TabWidget:</p>

<blockquote>
  <p>Error during post inflation process:
  TabHost requires a TabWidget with id
  "android:id/tabs". View found with id
  'tabs' is
  'com.android.layoutlib.bridge.MockView'
  The following classes could not be
  found:
  - TabWidget</p>
</blockquote>

<hr>

<p>Answers would be much appreciated </p>
