请教老师，下面代码写在AfterExpandNode，如果子节点数量大于1，无法实现折叠，

想实现，点击一个父节点，该父节点下所有子节点全部展开，其他父节点下的子节点全部收缩

If flag = True Then
For Each nd As WinForm.TreeNode In e.node.nodes
    If nd.Nodes.Count > 0 Then
        flag = False
    End If
Next
Else
    For Each nd1 As WinForm.TreeNode In e.Sender.AllNodes
        If e.node.FullName.StartsWith(nd1.FullName) = False Then
            nd1.Collapse
        End If
    Next
End If

Dim p = e.node.ParentNode
If p Is Nothing Then p = e.sender
For Each n As WinForm.TreeNode In p.Nodes
    If n.name <> e.Node.name Then
        n.CollapseAll
    End If
Next

e.node.ExpandAll