unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  comctrls, StdCtrls, menus;

const
  UNIQUE_ID = $03BF;  // уникальный идентификатор для горячей клавиши

type
  TForm1 = class(TForm)
    HotKey  : THotKey;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure HotKeyExit(Sender: TObject);
  private
    { Private declarations }
  public
 procedure HotKeyMsgHandler(var message : TMessage); message WM_HOTKEY;
    procedure RegisterHotKeyId;
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.HotKeyMsgHandler(var message: TMessage);
begin
  SetForegroundwindow(Form1.Handle);
end;

procedure TForm1.RegisterHotKeyId;
var
  virt_key : word;
  fkMod    : word;
  shift_state : TShiftState;
begin
  fkMod := 0;
  ShortCutToKey(HotKey.HotKey, virt_key, shift_state);
  if ssShift in shift_state then fkMod := fkMod OR MOD_SHIFT;
  if ssAlt in shift_state   then fkMod := fkMod OR MOD_ALT;
  if ssCtrl in shift_state  then fkMod := fkMod OR MOD_CONTROL;
  RegisterHotKey(Form1.Handle, UNIQUE_ID, fkMod, virt_key);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  RegisterHotKeyId;
  // кнопка для того чтобы зарегистрировать новую горячую клавишу
  Button1.Caption :='Применить';
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  UnRegisterHotKey(Form1.Handle, UNIQUE_ID);
end;

procedure TForm1.HotKeyExit(Sender: TObject);
begin
  UnRegisterHotKey(Form1.Handle, UNIQUE_ID);
  RegisterHotKeyId;
end;

end.