Обратиться к вложенному контролу (TextBox в ListBox)

TextBox1.Text = "Hello, World!"

Dim myTextBox As New TextBox
ListBox1.Items.Add(myTextBox)

myTextBox.Text = "Hello, World!"

Class MainWindow 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles Button1.Click
        myTextBox.Text = "Hello, World!"
    End Sub
End Class

For Each item In MyListBox.Items
      item.text = "Hello, World!"
Next

For Each stakeItem In TBCHelper.StakePlan
    stakeItem.Text = stakeitem.stake
Next

Class MainWindow 
    Private Sub MainWindow_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        Dim MyListBox As New ListBox
        MyListBox.Items.Add(New TextBox)
        MyListBox.Items.Add(New TextBox)
        MyListBox.Items.Add(New TextBox)
        Dim n As Integer
        For Each TextBox In MyListBox.Items
            n += 1
            TextBox.text = "Добавили в " & n & "-й Textbox число " & n
        Next
        Mygrid.Children.Add(MyListBox)
    End Sub
End Class

For Each myTextBox In MyListBox.Items
       n += 1
       myTextBox.text = "Добавили в " & n & "-й Textbox число " & n
Next

For Each myTextBox As TextBox In MyListBox.Items
       n += 1
       myTextBox.text = "Добавили в " & n & "-й Textbox число " & n
Next