Right, this is direct draw to AWT canvas, not off-screen rendering like the AwtPanel. I have not tested data sharing between contexts.
You’re right, it uses onscreen rendering with the optimized NEWT AWT bridge under the hood. If somebody needs some interoperability with JavaFX, I’ll have to wrap the GLJPanel into another abstraction for JMonkeyEngine like for JogAmp’s Ardor3D Continuation and LibGDX.
Edit.: GLJPanel uses offscreen rendering but it’s completely hidden for the developer and highly optimized.