protected override void OnPaint(PaintEventArgs e)
{
var g = e.Graphics;
var ratioX = Dpi.GetWidth(1);
var ratioY = Dpi.GetHeight(1);
g.FillRectangle(BorderColor.Brush(), new Rectangle(0, 0, Width, Height));
g.FillRectangle(BackgroundColor.Brush(), new Rectangle(ratioX, ratioY,
Width - ratioX * 2, Height - ratioY * 2));
}