Запретить запускать дубль программы, активировать при этом ранее запущенный экземпляр

program Project1;
uses
  Forms,
  Windows,
  Unit1 in 'Unit1.pas' {Form1};
{$R *.RES}
 
var
  HM: THandle;
function Check: boolean;
begin
  HM := OpenMutex(MUTEX_ALL_ACCESS, false, 'MyOwnMutex');
  Result := (HM <> 0);
  if HM = 0 then HM := CreateMutex(nil, false, 'MyOwnMutex');
end;
 
begin
  if Check then Exit;
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

program Project1;
 
uses
     WinTypes,
     WinProcs,
     SysUtils, 
     Forms,
     Unit1 in 'Unit1.pas' {Form1};
 
{$R *.RES}
 
type
   PHWND = ^HWND;
 
function EnumFunc(Wnd:HWND; TargetWindow:PHWND) : bool; export;
var
  ClassName : array[0..30] of char;
begin
  Result := true;
  if GetWindowWord(Wnd,GWW_HINSTANCE) = hPrevInst then 
    begin
      GetClassName( Wnd, ClassName, 30 );
      if StrIComp( ClassName, 'TApplication' ) = 0 then
        begin 
          TargetWindow^ := Wnd;
          Result := false;
        end; 
    end;
end;
 
procedure GotoPreviousInstance;
var
  PrevInstWnd : HWND;
begin
  PrevInstWnd := 0;
  EnumWindows( @EnumFunc, Longint( @PrevInstWnd ) );
  if PrevInstWnd <> 0 then
    if IsIconic( PrevInstWnd ) then 
      ShowWindow( PrevInstWnd, SW_RESTORE )
    else
      BringWindowToTop( PrevInstWnd );
end;
 
begin 
  if hPrevInst <> 0 then
    GotoPreviousInstance
  else
    begin
      Application.CreateForm(TForm1, Form1); 
      Application.Run;
  end;
end.

var
  HM: THandle;
function Check: boolean;
begin
  HM := OpenMutex(MUTEX_ALL_ACCESS, false, 'MyOwnMutex');
  Result := (HM <> 0);
  if HM = 0 then HM := CreateMutex(nil, false, 'MyOwnMutex');
end;
 
begin
  MessageId := RegisterWindowMessage(PChar('Some Unical Key'));
  if Check then
    PostMessage(HWND_BROADCAST,MessageId,0,0)
  else begin
    Application.Initialize;
    Application.CreateForm(TMainForm, MainForm);
  Application.Run;
  end;

procedure TMainForm.OnAppMessage(var M: TMsg; var Ret: Boolean);
begin
  if M.Message = MessageId then begin
    Ret := True;
    Show;
    SetForegroundWindow(MainForm.Handle);
  end;
end;

var
  MainForm: TMainForm;
  MessageId: Cardinal;