/// <summary>
        ///  绘制按钮
        /// </summary>
        /// <param name="g">The Graphics.</param>
        /// User:Ryan  CreateTime:2011-08-02 14:23.
        private void DrawButton(Graphics g)
        {
            Rectangle        btnRect;
            EnumControlState btnState = this.GetComboBoxButtonPressed() ? EnumControlState.HeightLight : EnumControlState.Default;

            btnRect = new Rectangle(this.ButtonRect.X, this.ButtonRect.Y - 1, this.ButtonRect.Width + 1 + this._Margin, this.ButtonRect.Height + 2);
            RoundRectangle btnRoundRect = new RoundRectangle(btnRect, new CornerRadius(0));

            //Blend blend = new Blend(3);
            //blend.Positions = new float[] { 0f, 0.5f, 1f };
            //blend.Factors = new float[] { 0f, 1f, 0f };
            GDIHelper.FillRectangle(g, btnRoundRect, SkinManager.CurrentSkin.DefaultControlColor);
            Size btnSize = new Size(12, 7);

            GDIHelper.DrawArrow(g, ArrowDirection.Down, btnRect, btnSize, 0f, Color.FromArgb(30, 178, 239));
            Color lineColor = SkinManager.CurrentSkin.BorderColor;

            GDIHelper.DrawGradientLine(g, lineColor, 90, btnRect.X, btnRect.Y, btnRect.X, btnRect.Bottom - 1);
        }