Basta buscar en la ayuda de Delphi y encontrarás un ejemplo bastante claro:
Código Delphi
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procedure TMyDialogBox.OKButtonClick(Sender: TObject);
begin
ModalResult := mrOK; end;
procedure TMyDialogBox.CancelButtonClick(Sender: TObject);
begin
ModalResult := mrCancel;
end;
This code brings up the modal dialog from Form1 when a button is clicked. It causes a Beep if the OK button is clicked.
procedure TForm1.Button1Click(Sender: TObject);
begin
if MyDialogBox1.ShowModal = mrOK then Beep;
end;