[NumLock]

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TLostComponent = class(TComponent)
  public
    constructor Create(AOwner: TComponent); override;
  end;

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure WMUSER(var Msg: TMessage); message WM_USER+1973;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TlostComponent }

constructor TLostComponent.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  if AOwner is TForm then SendMessage(TForm(AOwner).Handle, WM_USER+1973, 0, 0)
  else SendMessage(Screen.Forms[0].Handle, WM_USER+1973, 0, 0);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  TLostComponent.Create(Application);
  TLostComponent.Create(Self);
end;

procedure TForm1.WMUSER(var Msg: TMessage);
begin
  ShowMessage('ok');
end;

end.