Attaching to windows GUI

Okay, I'm going to look at my problem from another, more clean, perspective.
I have seen the occasional blitz program which seems to be using the windows UI, and I have heard the occasional chatter about such things.
Is it possible to have a dll written in C++ or such which draws the entire program's GUI using a proper windows gui, and then have blitz accessing that dll to draw it's own 3d viewport in one single window? I don't care how really this is done actually as long as it's quick, so to rephrase: Can I use C++ for an open-ended one-time GUI, while using blitz3d for the 3d stuff, which is floating around in its own window just like the rest, in the same program?

I think that the examples of (previewable) Blitz-based screensavers prove that this is possible... you need some way of getting hold of the window handle + canvas of GUI widget. I made a B3D screensaver about a year ago and remember spending ages with Winspector (Borland tool) to do just that in order to find the Screensaver Preview canvas used by the Control Panel.

A lot of that was groping in the dark for me - new territory and all that, but I did eventually get it working. Unfortunately, my laptop HD is very poorly at the moment and I am offloading files to backup at about 3 bytes per day (seems like it !) so example code will have to come from elsewhere.