unit Unit1;

interface

uses
  Windows, Classes, Controls, Forms, Buttons, StdCtrls;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Button1: TButton;
    procedure FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
     if ((key=vk_left) and (ssShift in Shift)) then label1.Visible:=not label1.Visible;
end;

end.

procedure MyWMKeyDown(var Message: TWMKeyDown); message WM_KEYDOWN;
.............
implementation
var fl:boolean;
{$R *.dfm}
procedure TForm1.MyWMKeyDown(var Message: TWMKeyDown);
begin
     if (fl) and (Message.CharCode = vk_left) then
       label1.Visible:=not label1.Visible;
end;
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
     //if ((key=vk_left) and (ssShift in Shift)) then label1.Visible:=not label1.Visible;
     if key=vk_shift then fl := true;
end;

procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
     //if ((key=vk_left) and (ssShift in Shift)) then label1.Visible:=not label1.Visible;
     if not (key=vk_shift) then fl := false;
end;