draw black 50% transparent box

_boxBrush.Color = new Color(0,0,0); //Black
_boxBrush.Brush.Opacity = 0.5f; // 50% opacity
Rectangle r = Rectangle.Create(x - playerScreen.Z / 4 - 3, y - 5, w + 3, h + 5);
gfx.DrawRectangle(_boxBrush, r, 1);
gfx.FillRectangle(_boxBrush, r);