core/src/in/srain/cube/app/CubeFragment.java
@Override
    public void onResume() {
        super.onResume();
        if (!mFirstResume) {
            onBack();
        }
        if (mFirstResume) {
            mFirstResume = false;
        }
        if (DEBUG) {
            showStatus("onResume");
        }
    }
@Override
    public void onResume() {
        super.onResume();
        if (!mFirstResume) {
            onBack();
        }
        if (mFirstResume) {
            mFirstResume = false;
        }
        if (DEBUG) {
            showStatus("onResume");
        }
    }
Only when Activity resume, not very precise.
When activity recover from partly invisible, onBecomesPartiallyInvisible will be triggered.