1.open from notification bar 
2.press home return to desttop
3.open from app icon

problem:2 instance of SampleTabsDefault, need to exit twice.

```
    Intent intent = new Intent(_context, SampleTabsDefault.class);
    intent.setFlags(/*Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP |*/ Intent.FLAG_ACTIVITY_NEW_TASK);
    PendingIntent activity = PendingIntent.getActivity(_context, 0, intent, 0);
    notification.contentIntent = activity;

```