Animation transition between activities in ActivityGroup?

[HaoZhe Xu]

I use ActivityGroup to manage activities, I want to add animation when change activity, the code I used to change to next activity is:

Intent intent = new Intent(getParent(), AnotherActivity.class);
TabGroupActivity parentActivity = (TabGroupActivity) getParent();
parentActivity.startChildActivity("AnotherActivity", intent);

And inside startChildActivity:

Window window =getLocalActivityManager().startActivity(Id,intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
if (window != null) {
    View view = window.getDecorView();
    mIdList.add(Id);
    setContentView(view);
}

TabGroupActivity is just an ActivityGroup, provides some useful methods. With the above code, what/where do I add to enable animation?

Thanks!