If we using DirectColor visuals then we can use the colormap to provide a gamma ramp.  This allows the ramp to affect just the window rather than everything.
If we using DirectColor visuals then we can use the colormap to provide
a gamma ramp.  This allows the ramp to affect just the window rather than
everything.

voyageur/openglide,voyageur/openglide,voyageur/openglide