XFree86 + Matrox G450 + dualhead


I have a Matrox G450 board with dualhead capability,
and I would like to make XFree86 work with this board
under QNX 6.3.0.

I was able to make this configuration work under Linux
with XFree86 4.3.0. And also with photon under QNX.

The situation at the moment is that I’m able to start
the XServer, and get image on one of the displays,
while the other stays blank.

Did anybody make such a configuration work under QNX ?