Using fragments with NativeActivity

I have a fully working C++/OpenGL engine that I ported over to Android using their supplied NativeActivity. But I'm now tasked with integrating it to an older project which was 100% Java, with plenty of Fragments.

My question is simple : Is it possible to show/use a Fragment over a NativeActivity?

Note: I'm using a custom Java class that derives from NativeActivity to be able to catch some events that are not available to the the C++ layer. So the proposed solution can be either in Java or C++.

I have tried sample code from various source to show the fragment from Java :

public class CustomNativeActivity extends NativeActivity
{
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        startFragment();
    }

    public void startFragment() {
        TestNativeFragment fragment = new TestNativeFragment();
        getFragmentManager().beginTransaction().replace(android.R.id.content, fragment).commit();
    }
}

No crash, no message in the console after the fragment transaction. Just my OpenGL but no signs of my fragment.

Thanks for any help!

Since this project is highly reliant on Java and Fragments, I decided to ditch the NativeActivity approach and instead add a GLSurfaceView in my layout file, and from there, call in the c++ engine's functions via JNI. If anyone is interested in the code please let me know. Thanks for the suggestions.