'// ParentForm
        For Each f As Form In Me.MdiChildren
            If TypeOf (f) Is frmAuftrag Then
                CType(f, frmAuftrag).PrintDialog1.ShowDialog()
            End If
        Next
 
        '// oder:
 
        Dim f As Form = Me.ActiveMdiChild()
        If TypeOf (f) Is frmAuftrag Then
          CType(f, frmAuftrag).PrintDialog1.ShowDialog()
        End If