Enum Child Windows

Hey guys ;)

I have had some previos help from Half on this topic but i tried my own idea and i have some problems.
I need to find a child in internet explorer which is a popup window. The project contains a listbox named listbox1 and a button named button1.

Problem: I cant find the child window.

Example:
When you log in the router a window comes up requesting your username and password.
I need to find that window knowing only the first word.

Tnx :)

Code:

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Imports System.Runtime.InteropServices
Imports System.Text

Public Class Form1
    <DllImport("User32.dll")> _
      Private Shared Function EnumChildWindows _
          (ByVal WindowHandle As IntPtr, ByVal Callback As EnumWindowProcess, _
          ByVal lParam As IntPtr) As Boolean
    End Function
    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function GetWindowText(ByVal hwnd As IntPtr, _
                      ByVal lpString As StringBuilder, _
                      ByVal cch As Integer) As Integer
    End Function

    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function GetWindowTextLength(ByVal hwnd As IntPtr) As Integer
    End Function


    Public Delegate Function EnumWindowProcess(ByVal Handle As IntPtr, ByVal Parameter As IntPtr) As Boolean
    Public Declare Function FindWindow Lib "user32.dll" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer


    Public Function GetChildWindows(ByVal ParentHandle As IntPtr) As IntPtr()
        Dim ChildrenList As New List(Of IntPtr)
        Dim ListHandle As GCHandle = GCHandle.Alloc(ChildrenList)
        Try
            EnumChildWindows(ParentHandle, AddressOf EnumWindow, GCHandle.ToIntPtr(ListHandle))
        Finally
            If ListHandle.IsAllocated Then ListHandle.Free()
        End Try
        Return ChildrenList.ToArray
    End Function

    Private Function EnumWindow(ByVal Handle As IntPtr, ByVal Parameter As IntPtr) As Boolean
        Dim ChildrenList As List(Of IntPtr) = GCHandle.FromIntPtr(Parameter).Target
        If ChildrenList Is Nothing Then Throw New Exception("GCHandle Target could not be cast as List(Of IntPtr)")
        ChildrenList.Add(Handle)
        ListBox1.Items.Add(Handle)
        Return True
    End Function


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim iHwnd As Long = 0
        iHwnd = FindWindow(vbNullString, "Internet Explorer cannot display the webpage - Windows Internet Explorer")
        GetChildWindows(iHwnd)
    End Sub

    Public Function GetText(ByVal hWnd As IntPtr) As String
        Dim length As Integer
        If hWnd.ToInt32 <= 0 Then
            Return Nothing
        End If
        length = GetWindowTextLength(hWnd)
        If length = 0 Then
            Return Nothing
        End If
        Dim sb As New System.Text.StringBuilder("", length + 1)

        GetWindowText(hWnd, sb, sb.Capacity)
        Me.Text = sb.ToString
        Return sb.ToString()
    End Function

    Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
        GetText(ListBox1.SelectedItem)
    End Sub
End Class

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