通过设置，Winform Panel可以显示特定边框的阴影效果。使用以下代码可以实现绘制不同边框的阴影效果：

static Image shadowDownRight = new Bitmap(typeof(ShadowPanel), "Images.tshadownright.png");//下右

static Image shadowDown = new Bitmap(typeof(ShadowPanel), "Images.tshadown.png");//下

static Image shadowRight = new Bitmap(typeof(ShadowPanel), "Images.tshadowright.png");//右

static Image shadowTop = new Bitmap(typeof(ShadowPanel), "Images.tshadowtop.png");//上

static Image shadowLeft = new Bitmap(typeof(ShadowP