解决方法
你的意思是这样的吗？
procedure TForm1.Button1Click(Sender: TObject);
var
Form: TForm;
Lbl: TLabel;
Btn: TButton;
begin
Form := TForm.Create(nil);
try
Form.BorderStyle := bsDialog;
Form.Caption := 'My Dynamic Form!';
Form.Position := poScreenCenter;
Form.ClientWidth := 400;
Form.ClientHeight := 200;
Lbl := TLabel.Create(Form);
Lbl.Parent := Form;
Lbl.Caption := 'Hello World!';
Lbl.Top := 10;
Lbl.Left := 10;
Lbl.Font.Size := 24;
Btn := TButton.Create(Form);
Btn.Parent := Form;
Btn.Caption := 'Close';
Btn.ModalResult := mrClose;
Btn.Left := Form.ClientWidth - Btn.Width - 16;
Btn.Top := Form.ClientHeight - Btn.Height - 16;
Form.ShowModal;
finally
Form.Free;
end;
end;