public void RequestRenderbuffer( GLESSurfaceDescription surface )
{
if (surface.Buffer == null)
return;
RBFormat key = new RBFormat(surface.Buffer.GLFormat, surface.Buffer.Width, surface.Buffer.Height, surface.NumSamples);
Utilities.Contract.Requires(_renderBuffer.ContainsKey(key));
Utilities.Contract.Requires(_renderBuffer[key].Buffer == surface.Buffer);
RBRef refval = _renderBuffer[key];
refval.RefCount++;
_renderBuffer[key] = refval;
}