主题：如何判断目录树当前可见节点数量

Dim trv As WinForm.TreeView = e.Form.Controls("TreeView1")
Dim sum As Double = 0
For Each nd As WinForm.TreeNode In trv.AllNodes
    If nd.IsExpanded Then
        sum += nd.Nodes.Count
    End If
Next
msgbox(sum+trv.Nodes.count)