Thanks all for the tips. I have A7 Commercial.

I want to call the render routine for my debug GUI after GS renders each frame, and hook in my input event handlers as well so they can override all or selected buttons/keys.

I'm not sure I understand what this means:

"You can also take a look an EndScene and Reset of the D3D-Device"

From the link to on_message I think I understand what hooking into functions entails. I'm using SwiftForth, which has provisions for callbacks, but it's hit and miss with different libraries. Hopefully it works with A7. If this works out it'll be very exciting because programming with my codebase in SwiftForth is a lot of fun.