Delphi Позволяет исходному немодальному окну нормально реагировать при отображении модального окна.

[Lomanu4]

unit Unit12;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
 
type
  TForm12 = class(TForm)
    btn1: TButton;
    btn2: TButton;
    procedure btn1Click(Sender: TObject);
    procedure btn2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
    procedure DoModalStart(ASender:TObject);
  public
    { Public declarations }
  end;
 
var
  Form12: TForm12;
 
implementation
uses unit13;
{$R *.dfm}
 
procedure TForm12.btn1Click(Sender: TObject);
var
  F:TForm;
begin
Form13:=TForm13.Create(Application);
Form13.Show;
end;
 
procedure TForm12.btn2Click(Sender: TObject);
begin
TForm.Create(Application).ShowModal;
end;
 
procedure TForm12.DoModalStart(ASender: TObject);
begin
Form13.Hide;
PostMessage(Form13.Handle,WM_APP,0,0);
end;
 
procedure TForm12.FormCreate(Sender: TObject);
begin
Application.OnModalBegin:=DoModalStart;
end;
 
end.