private void DrawGradient(Context g)
{
Rectangle rect = GradientRectangle;
Gradient pat = new LinearGradient(rect.X, rect.Y, rect.X,
rect.Y + rect.Height);
pat.AddColorStop (0, MaxColor);
pat.AddColorStop (1, new Cairo.Color (0, 0, 0));
g.Rectangle (rect);
g.Pattern = pat;
g.Fill();
}