Namespace Tools
    Public Class EnumWindows
        Public Shared Function EnumWindows() As List(Of IntPtr)
            Dim handleList As New List(Of IntPtr)

            HandleLists.Add(handleList)
            Dim handleIndex As Integer = HandleLists.IndexOf(handleList)
            Win32.EnumWindows(AddressOf EnumCallback, handleIndex)
            HandleLists.Remove(handleList)

            Return handleList
        End Function

        Public Shared Function EnumChildWindows(ByVal hWndParent As IntPtr) As List(Of IntPtr)
            Dim handleList As New List(Of IntPtr)

            HandleLists.Add(handleList)
            Dim handleIndex As Integer = HandleLists.IndexOf(handleList)
            Win32.EnumChildWindows(hWndParent, AddressOf EnumCallback, handleIndex)
            HandleLists.Remove(handleList)

            Return handleList
        End Function

        Private Shared ReadOnly HandleLists As New List(Of List(Of IntPtr))

        Private Shared Function EnumCallback(hwnd As Integer, lParam As Integer) As Boolean
            HandleLists(lParam).Add(hwnd)
            Return True
        End Function

        ' ReSharper disable ClassNeverInstantiated.Local
        Private Class Win32
            ' ReSharper restore ClassNeverInstantiated.Local
            Public Delegate Function EnumWindowsProc(ByVal hwnd As Integer, ByVal lParam As Integer) As Boolean
            Declare Function EnumWindows Lib "user32" (ByVal lpEnumFunc As EnumWindowsProc, ByVal lParam As Integer) As Boolean
            Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As IntPtr, ByVal lpEnumFunc As EnumWindowsProc, ByVal lParam As Integer) As Boolean
        End Class
    End Class
End Namespace