Hi,

I'm not using GLCtrl but DHCtrl directly...OpenCascade library already has the OpenGL layer, just needs an hwnd.

EDIT
Thinking a bit more... I could use the generic interface of OpenCascade, which should do the job with your GLCtrl
control. It's called Aspect_NeutralWindow, in replacement of WNT_Window and X11_Window, and requires the "manual" context creation, which your control does.