64.9 Receiving Multi-Window Notifications
An activity will receive notification that it is entering or exiting multi-window mode if it overrides the onMultiWindowModeChanged() callback method. The first argument passed to this method is true on entering multi-window mode, and false when the activity exits the mode. The new configuration settings are contained within the Configuration object passed as the second argument:
@Override
public void onMultiWindowModeChanged(boolean isInMultiWindowMode,
Configuration newConfig) {
super.onMultiWindowModeChanged(isInMultiWindowMode, newConfig);
if (isInMultiWindowMode) {
...