title: what is "BasicDream" in android ICS?
body: <p>I read the Launcher source code which version is ICS. There is a <code>RocketLauncher</code> class which extends <code>BasicDream</code>. what is <code>BasicDream</code>? what can <code>BasicDream</code> do? I can find this line <code>import android.support.v13.dreams.BasicDream;</code>, but I can't find any information about it on Internet. Please give me some information to understand it. Thanks!</p>
  
  <p>Update: I found those code in launcher manifest.xml
  <code>&lt;activity android:name="com.android.launcher2.RocketLauncher"
              android:label="@string/dream_name"
              android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"&gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN" /&gt;
                  &lt;category android:name="android.intent.category.DEFAULT" /&gt;
                  &lt;category android:name="android.intent.category.DREAM" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt;</code></p>
  
  <p>There is a new category <code>android.intent.category.DREAM</code>, what is it used to do? That RocketLauncher is an <code>Activity</code>? </p>