动态加入控件的显示有关问题

动态加入控件的显示问题
为什么以下代码显示不了我要加入的picturebox？


PictureBox   pb   =   new   PictureBox();
pb.Location   =   new   System.Drawing.Point(176,72);
pb.Size   =   new   Size(80,13);
pb.BorderStyle   =   BorderStyle.None;
Graphics   g1   =   pb.CreateGraphics();
g1.FillRectangle(Brushes.BlueViolet,180,73,50,7);

this.Controls.Add(pb);

this.Refresh();

[解决办法]
PictureBox pb = new PictureBox();
pb.Location = new System.Drawing.Point(176, 72);
pb.Size = new Size(80, 13);
pb.BorderStyle = BorderStyle.FixedSingle;
Graphics g1 = pb.CreateGraphics();
g1.FillRectangle(Brushes.BlueViolet, 0, 0, 50, 7);

this.Controls.Add(pb);

this.Refresh();

这就看得到了
[解决办法]
估计是你的事件选择错了．