treeview 保持选中状态

发现当treeview控件失去焦点的时候，会丢失选中状态的指示（条目的蓝色背景）。如果想要保持，只要设置treeview的一个属性即可：

this.treeView1.HideSelection = false;

但是，发现阴影很浅，但是聊胜于无。

在博客园上找到了“大气象学习园地”的一篇博文（链接），刚好说到这个事，他通过重写DrawMode()来控制选中节点颜色，把他的代码也贴上：

public FrmMain()
{InitializeComponent();treeView1.HideSelection = False;//自已绘制this.treeView1.DrawMode = TreeViewDrawMode.OwnerDrawText;this.treeView1.DrawNode += new DrawTreeNodeEventHandler(treeView1_DrawNode);
}//在绘制节点事件中，按自已想的绘制
private void treeView1_DrawNode(object sender, DrawTreeNodeEventArgs e)
{e.DrawDefault = true; //我这里用默认颜色即可，只需要在TreeView失去焦点时选中节点仍然突显return;if ((e.State & TreeNodeStates.Selected) != 0){//演示为绿底白字
        e.Graphics.FillRectangle(Brushes.DarkBlue, e.Node.Bounds);Font nodeFont = e.Node.NodeFont;if (nodeFont == null) nodeFont = ((TreeView)sender).Font;e.Graphics.DrawString(e.Node.Text, nodeFont, Brushes.White,Rectangle.Inflate(e.Bounds, 2, 0));}else{e.DrawDefault = true;}if ((e.State & TreeNodeStates.Focused) != 0){using (Pen focusPen = new Pen(Color.Black)){focusPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;Rectangle focusBounds = e.Node.Bounds;focusBounds.Size = new Size(focusBounds.Width - 1,focusBounds.Height - 1);e.Graphics.DrawRectangle(focusPen, focusBounds);}}}