public override void DrawWindowBorder(Canvas2D canvas, Color color, float x, float y, float w, float h)
{
var topColor = Color.Lerp(color, Color.White, 0.7f);
canvas.SetLinearGradientFill(new Vector2(x, y), new Vector2(x, y + h), new GradientStop(0, topColor), new GradientStop(1, color));
canvas.DrawRectangle(x, y, w, h);
}