看起來(lái)只有在子窗體的 Activate 事件里做文章
但是也有問(wèn)題，就是要打開(kāi)的窗體一定會(huì)打開(kāi)，

Dim sLastForm As String
Dim sThisForm As String '正要打開(kāi)的子窗體的caption屬性

Private Sub Form_Activate()
Debug.Print "Form_Activate" & Me.Caption
sThisForm = Me.Caption
End Sub

Private Sub Form_Deactivate()
Debug.Print "Form_Deactivate" & Me.Caption
sLastForm = Me.Caption
End Sub