private void treeView1_MouseUp(object sender, MouseEventArgs e)
        {
            TreeNode td = this.treeView1.GetNodeAt(e.X, e.Y);
            if (td == null)
                this.treeView1.SelectedNode = null;
        }

------解决方案--------------------
探讨

  
C# codeprivate void treeView1_MouseUp(object sender, MouseEventArgs e)
        {
            TreeNode td = this.treeView1.GetNodeAt(e.X, e.Y);
            if (td == null)
                this.treeView1.SelectedNode = null;
        }