- oldFocus
- The previously focused view, if any.
- newFocus
- The newly focused View, if any.
Callback method to be invoked when the focus changes in the view tree. When the view tree transitions from touch mode to non-touch mode, oldFocus is null. When the view tree transitions from non-touch mode to touch mode, newFocus is null. When focus changes in non-touch mode (without transition from or to touch mode) either oldFocus or newFocus can be null.