Treeview控件失去焦点，将选择的节点设置为高亮显示

1. 修改TreeView的属性
   

   1 this.treeView1.HideSelection = false;
   2 this.treeView1.DrawMode = TreeViewDrawMode.OwnerDrawText;

2. 添加treeView1_DrawNode事件

   1 private void treeView1_DrawNode(object sender, DrawTreeNodeEventArgs e)
   2 {
   3   e.DrawDefault = true;//由操作系统绘制节点，默认值为false
   4 }

    1 private void treeView1_DrawNode(object sender, DrawTreeNodeEventArgs e)
    2 {
    3     if ((e.State & TreeNodeStates.Selected) != 0)
    4     {
    5         e.Graphics.FillRectangle(Brushes.DodgerBlue, e.Node.Bounds);
    6 
    7         Font nodeFont = e.Node.NodeFont;
    8         if (nodeFont == null) nodeFont = ((TreeView)sender).Font;
    9         e.Graphics.DrawString(e.Node.Text, nodeFont, Brushes.White, Rectangle.Inflate(e.Bounds, 2, 0));
   10     }
   11     else
   12     {
   13         e.DrawDefault = true;
   14     }
   15 
   16     if ((e.State & TreeNodeStates.Focused) != 0)
   17     {
   18         using (Pen focusPen = new Pen(Color.White))
   19         {
   20             focusPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;
   21             Rectangle focusBounds = e.Node.Bounds;
   22             focusBounds.Size = new Size(focusBounds.Width - 1,
   23             focusBounds.Height - 1);
   24             e.Graphics.DrawRectangle(focusPen, focusBounds);
   25         }
   26     }
   27 }