title: Cannot resolve android.support.v7.app.AlertDialog
body: <p>I cannot resolve android.support.v7.app.AlertDialog. this error.its always red in my eclipse. Despite I have the android-support-v7-appcompat.jar in my libs folder, and am able use android.support.v7.app.ActionBarActivity;
  and android.support.v7.widget.Toolbar;</p>