How to make a Wnd with RAW API

{
WndCreator written by Simone Di Cicco - Italy
mail: simone.dicicco@tin.it
site: http://www.devresource.net

with the RAW API, you can develop applications
without the VCL, this idea is also called XCL
}

const
  AppName = 'WndApp';

function WndProc(HWnd: HWND; Msg: UINT;
  wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
begin
  case Msg of
    WM_DESTROY:
      begin
        PostQuitMessage(0);
        Result := 0;
      end
    else
      Result := DefWindowProc(HWnd,Msg,WParam,LParam);
  end;
end;

var
  WndClass: TWndClass;
  Handle: HWND;
  Msg: TMsg;
  Result: Integer;
begin
  with WndClass do begin
    style := CS_VREDRAW or CS_HREDRAW;
    lpfnWndProc := @WndProc;
    cbClsExtra := 0;
    cbWndExtra := 0;
    hInstance := SysInit.HInstance;
    hIcon := LoadIcon(HInstance,IDI_APPLICATION);
    hCursor := LoadCursor(HInstance,IDC_ARROW);
    hbrBackground := GetStockObject(LTGRAY_BRUSH);
    lpszMenuName := nil;
    lpszClassName:= AppName;
  end;
  RegisterClass(WndClass);
  Handle := CreateWindow(AppName,'RAW API WND, Smile :)',
    WS_OVERLAPPEDWINDOW,
    CW_USEDEFAULT,CW_USEDEFAULT,
    CW_USEDEFAULT,CW_USEDEFAULT,
    0,0,HInstance,nil);
  ShowWindow(Handle,SW_NORMAL);
  UpdateWindow(Handle);
  while GetMessage(Msg,0,0,0) do begin
    TranslateMessage(Msg);
    DispatchMessage(Msg);
  end;
end.