ShowDialog from Word-event-procedure

[zaharius]

I make project with reference to Microsoft Word Object Library, Form1 (eazy windows form), Dialog1 (dialog form). In Form1 I insert Button1 and Button2.
The code:
Code:

Imports Microsoft.Office.Interop

Public Class Form1
    Private WithEvents wdApp As New Word.Application
    Private WithEvents wdDoc As New Word.Document
    Private txtBox As New TextBox

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dialog1.Controls.Add(txtBox) ‘make textbox programmatically
        txtBox.Visible = True
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dialog1.ShowDialog() ‘call dialog from windows form – textbox is visible
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        wdDoc = wdApp.Documents.Add
        wdDoc.ActiveWindow.Visible = True
    End Sub

    Private Sub wdApp_WindowBeforeRightClick(ByVal Sel As Microsoft.Office.Interop.Word.Selection, ByRef Cancel As Boolean) Handles wdApp.WindowBeforeRightClick
        Cancel = True
        Dialog1.ShowDialog() ‘call dialog from Word events – textbox is unvisible
    End Sub
End Class

I press Button2, right-click in Word-document and see loaded Dialog1 without textbox!
Haw call ShowDialog from Word event procedure and show programmatically created controls?