How to make MessageDlg centered on owner form

Question

I'd like that MessageDlg appear centered on its parent form. Any suggestions on how to accomplish this in Delphi 2010?

I found the code below here: http://delphi.about.com/od/formsdialogs/l/aa010304a.htm but it's not working for me. The pop-up still is not centered on the owner form. (It's not clear to me how the method would actually know the owner form...)

 function TForm1.MessageDlg(const Msg: string; DlgType: TMsgDlgType;
   Buttons: TMsgDlgButtons; HelpCtx: Integer): Integer;
 begin
   with CreateMessageDialog(Msg, DlgType, Buttons) do
     try
       Position := poOwnerFormCenter;
       Result := ShowModal
     finally
       Free
     end
 end;

Answer 1

The dialog doesn't have a relationship with the instance of TForm1. It would not be hard to set the position of the form manually, but I bet someone who is more familiar with this area of the VCL will know how to do it a cleaner way.

Personally I never use the Position property and use my own code to position all my forms because I've never been satisfied with the performance of the Position property.

UPDATE: You can change the owner of the dialog using Self.InsertComponent(Dialog). You'd have to store your dialog into a local variable, say, Dialog, for this to work:

function TForm1.MessageDlg(const Msg: string; DlgType: TMsgDlgType;
  Buttons: TMsgDlgButtons; HelpCtx: Integer): Integer;
var
  Dialog: TForm;
begin
  Dialog := CreateMessageDialog(Msg, DlgType, Buttons);
  try
    Self.InsertComponent(Dialog);
    Dialog.Position := poOwnerFormCenter;
    Result := Dialog.ShowModal
  finally
    Dialog.Free
  end
end;