title: Activity in TabHost
body: <p>I use a TabHost.
  The below code to call AActivity.</p>
  
  <pre><code>intent = new Intent().setClass(this, AActivity.class);
  spec = tabHost.newTabSpec("A").setIndicator("A", res.getDrawable(R.drawable.icon)).setContent(intent);
  tabHost.addTab(spec);
  </code></pre>
  
  <p>And it is in the tab.
  But in AActivity I call BActivity.
  The BActivity will open new page, but not in the tab.
  How to let it on the tab frame?
  AActivity use below code to call BActivity:</p>
  
  <pre><code>it = new Intent(this, BActivity.class);
  startActivity(it);
  </code></pre>