public override void SetBitmapPixel(object handle, int x, int y, Xwt.Drawing.Color color)
{
NSImage img = (NSImage)handle;
NSBitmapImageRep bitmap = img.Representations().OfType <NSBitmapImageRep> ().FirstOrDefault();
if (bitmap != null)
{
bitmap.SetColorAt(color.ToNSColor(), x, y);
}
else
{
throw new InvalidOperationException("Not a bitmnap image");
}
}