[Android] App Widget

1. Docs
   
   • http://blogold.chinaunix.net/u/9577/showart.php?id=2538388
   • Widget Design Guidelines
     http://developer.android.com/guide/practices/ui_guidelines/widget_design.html
   • http://developer.android.com/guide/topics/appwidgets/index.html
     
   • xxx
     
2. Summary
   App Widgets are miniature application views that can be embedded in other applications (such as the Home screen) and receive periodic updates.
   
   More details: <> http://blogold.chinaunix.net/u/9577/showart.php?id=2538386
   
3. Classes
4. xxx