/// 
        /// 实现“背景色渐变”的功能。【尚不完善】        /// 
        ///         protected override void OnPaintBackground(PaintEventArgs e)        {            int y, dy;            //y=this.Height-this.ClientRectangle.Height;            y = this.ClientRectangle.Location.Y;            dy = this.ClientRectangle.Height / 256;            for (int i = 255; i >= 0; i--)            {                              Color c = new Color();                c = Color.FromArgb(Convert.ToInt32(textBox1.Text.ToString()), i,Convert.ToInt32(textBox2.Text.ToString()));                SolidBrush sb = new SolidBrush(c);                Pen p = new Pen(sb, 100);                e.Graphics.DrawRectangle(p,this.ClientRectangle.X, y, this.Width,y+dy);                y = y + dy;            }        }