您正在寻找的是TreeView上的HideSelection属性。

来自MSDN：

获取或设置一个值，该值指示即使树视图失去焦点，选定的树节点是否仍保持突出显示。
友情链接：http://msdn.microsoft.com/en-us/library/system.windows.forms.treeview.hideselection.aspx

验证码：

TreeView.HideSelection = false;

它仍然显示，但只有在浅灰色，这取决于您的屏幕和当前设置可以在可见附近！
停止OnDrawNode事件。因此，您创建了一个新类（称为“SpecialTreeView”），它继承自Microsoft TreeView（如class SpecialTreeView : TreeView）。然后添加以下事件覆盖：

protected override void OnDrawNode(DrawTreeNodeEventArgs e)
{
    TreeNodeStates treeState = e.State;
    Font treeFont = e.Node.NodeFont ?? e.Node.TreeView.Font;

    // Colors.
    Color foreColor = e.Node.ForeColor;
    string strDeselectedColor = @"#6B6E77", strSelectedColor = @"#94C7FC";
    Color selectedColor = System.Drawing.ColorTranslator.FromHtml(strSelectedColor);
    Color deselectedColor = System.Drawing.ColorTranslator.FromHtml(strDeselectedColor);

    // New brush.
    SolidBrush selectedTreeBrush = new SolidBrush(selectedColor);
    SolidBrush deselectedTreeBrush = new SolidBrush(deselectedColor);

    // Set default font color.
    if (foreColor == Color.Empty)
        foreColor = e.Node.TreeView.ForeColor;

    // Draw bounding box and fill.
    if (e.Node == e.Node.TreeView.SelectedNode)
    {
        // Use appropriate brush depending on if the tree has focus.
        if (this.Focused)
        {
            foreColor = SystemColors.HighlightText;
            e.Graphics.FillRectangle(selectedTreeBrush, e.Bounds);
            ControlPaint.DrawFocusRectangle(e.Graphics, e.Bounds, foreColor, SystemColors.Highlight);
            TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds,
                                         foreColor, TextFormatFlags.GlyphOverhangPadding);
        }
        else
        {
            foreColor = SystemColors.HighlightText;
            e.Graphics.FillRectangle(deselectedTreeBrush, e.Bounds);
            ControlPaint.DrawFocusRectangle(e.Graphics, e.Bounds, foreColor, SystemColors.Highlight);
            TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds,
                                         foreColor, TextFormatFlags.GlyphOverhangPadding);
        }
    }
    else
    {
        if ((e.State & TreeNodeStates.Hot) == TreeNodeStates.Hot)
        {
            e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
            TextRenderer.DrawText(e.Graphics, e.Node.Text, hotFont, e.Bounds,
                                         System.Drawing.Color.Black, TextFormatFlags.GlyphOverhangPadding);
        }
        else
        {
            e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
            TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds,
                                         foreColor, TextFormatFlags.GlyphOverhangPadding);
        }
    }
}

编译代码后，您应该在设计器的工具箱中看到“SpecialTreeView”。使用相同的名称替换您的TreeView，唯一不同的是选择颜色。如果选择，则为selectedColor，如果未选择，则为deselectedColor。
我希望这能帮上忙。

快速解决方案：

设置属性：

• HideSelection = false;
• DrawMode = TreeViewDrawMode.OwnerDrawText;

然后在DrawNode事件处理程序中简单地执行：

private void treeView1_DrawNode(object sender, DrawTreeNodeEventArgs e) {
  e.DrawDefault = true;
}

在Windwos 7上，这会恢复旧的渲染，包括选区周围的虚线框（实际上看起来有点过时）。文本将为带焦点的白色，无焦点的黑色。背景保持蓝色和可见。
这个答案并不新鲜，其他人也包含这些步骤，但这是最低限度的需要（至少在Windows 7中，没有测试其他操作系统）。

不是绝对完美的解决方案，但相当接近：

treeView.HideSelection = false;
treeView.DrawMode = TreeViewDrawMode.OwnerDrawText;
treeView.DrawNode += (o, e) =>
{
    if (!e.Node.TreeView.Focused && e.Node == e.Node.TreeView.SelectedNode)
    {
        Font treeFont = e.Node.NodeFont ?? e.Node.TreeView.Font;
        e.Graphics.FillRectangle(Brushes.Gray, e.Bounds);
        ControlPaint.DrawFocusRectangle(e.Graphics, e.Bounds, SystemColors.HighlightText, SystemColors.Highlight);
        TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds, SystemColors.HighlightText, TextFormatFlags.GlyphOverhangPadding);
    }
    else
        e.DrawDefault = true;
};
treeView.MouseDown += (o, e) =>
{
    TreeNode node = treeView.GetNodeAt(e.X, e.Y);
    if (node != null && node.Bounds.Contains(e.X, e.Y))
        treeView.SelectedNode = node;
};

找到一个更简单的方法：
1.设置TreeView.HideSelection = True

1. decompose私有字段private TreeNode _lastSelectedNode = null;
   1.在TreeView.AfterSelect-Callback中添加以下内容：

private TreeNode _lastSelectedNode = null;
private void treeViewBenutzerverwaltung_AfterSelect(object sender, TreeViewEventArgs e)
{
    // Select new node
    e.Node.BackColor = SystemColors.Highlight;
    e.Node.ForeColor = SystemColors.HighlightText;
    if (_lastSelectedNode != null)
    {
        // Deselect old node
        _lastSelectedNode.BackColor = SystemColors.Window;
        _lastSelectedNode.ForeColor = SystemColors.WindowText;
    }
    _lastSelectedNode = e.Node;
}

与前一个类似，但外观更类似于Win10标准：

treeView.HideSelection = false;
treeView.DrawMode = TreeViewDrawMode.OwnerDrawText;

treeView.DrawNode += (o, e) =>
{
    if (e.Node == e.Node.TreeView.SelectedNode)
    {
        Font font = e.Node.NodeFont ?? e.Node.TreeView.Font;
        Rectangle r = e.Bounds;
        r.Offset(0, 1);
        Brush brush = e.Node.TreeView.Focused ? SystemBrushes.Highlight : Brushes.Gray;
        e.Graphics.FillRectangle(brush, e.Bounds);
        TextRenderer.DrawText(e.Graphics, e.Node.Text, font, r, SystemColors.HighlightText, TextFormatFlags.GlyphOverhangPadding);
    }
    else
        e.DrawDefault = true;
};

treeView.MouseDown += (o, e) =>
{
    TreeNode node = treeView.GetNodeAt(e.Location);
    if (node != null && node.Bounds.Contains(e.Location)) treeView.SelectedNode = node;
};