如何获取桌面上第二置顶的窗口句柄?

Option Explicit
Dim lngHandleA As Long
Dim lngHandleB As Long
Dim lngHandleC As Long
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Declare Function GetForegroundWindow Lib "user32" () As Long


Private Sub Form_Load()
    Form2.Show
    Form3.Show
    Form4.Show
    Form2.Caption = "A"
    Form3.Caption = "B"
    Form4.Caption = "C"
    lngHandleA = FindWindow(vbNullString, "A")      '窗体A句柄
    lngHandleB = FindWindow(vbNullString, "B")      '窗体B句柄
    lngHandleC = FindWindow(vbNullString, "C")      '窗体C句柄
    Timer1.Interval = 1000
End Sub

Private Sub Timer1_Timer()
    Dim lngP As Long
    lngP = GetForegroundWindow
    If lngP = lngHandleA Then
        Debug.Print "窗体A置顶"
    ElseIf lngP = lngHandleB Then
        Debug.Print "窗体B置顶"
    ElseIf lngP = lngHandleC Then
        Debug.Print "窗体C置顶"
    Else
        Debug.Print "三个窗体都没有置顶"
    End If
End Sub