private void pnl_MouseDown(object sender, MouseEventArgs e)
{
    chsman[nMousePositionOnChessboardX,nMousePositionOnChessboardY]=new Chessman();
}//nMousePostionOnChessboardX代表按钮在panel上的位置,它乘以50就是按钮的Location.X,Location.Y同理

 private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // Chessman
            // 
            this.Name = "Chessman";
            //this.MouseClick += new System.Windows.Forms.MouseEventHandler(this.Chessman_MouseClick);
            this.Paint += new System.Windows.Forms.PaintEventHandler(this.Chessman_Paint);
            this.ResumeLayout(false);

            this.Location = new Point(FormChessboard.nMousePositionOnChessboardX*nChessmanSizeWidth,
                FormChessboard.nMousePositionOnChessboardY*nChessmanSizeHeight);
            this.Size = new Size(nChessmanSizeWidth,nChessmanSizeHeight);
            Color clr = Color.FromArgb(255, 255, 255);
            this.BackColor = clr;
            this.BackgroundImage = global::ball2.Properties.Resources.Rad;
            // 我想把按钮的背景图片设置成Rad(已经存在的资源位图)
            // 报错如下:Error1' ball2.Properties.Resources' does not contain a definition for 'Rad'          
            pnl.Controls.Add(this);
            //现在轮到把按钮添加到formChessboard.pnl上,可是提示我pnl不存在
              //写成formChessboard.pnl.Controls.Add(this),提示我不是静态的
              //把那个pnl定义改成static时,formChessboard类初始化pnl又有错误:
            //Static member 'ball2.FormChessboard.pnl' cannot be accessed with an instance reference; 
qualify it with a type name instead                          

        }