Private Delegate Sub ShowFormHandler(ByVal frm As Form)
 
      Private Function ShowForm(ByVal frm As Form) As DialogResult
         Return frm.ShowDialog(pOwner)
      End Function

         Using frm As New ChangeFileDialog(sourceFile)
            Select Case DirectCast(frm.Invoke(New ShowFormHandler(AddressOf _
              ShowForm), New Object() {frm}), DialogResult)
               ' ...
            End Select
         End Using