Как проверить, включён ли ActiveDesktop

function IsActiveDeskTopOn: Boolean;
var
  h: hWnd;
begin
  h := FindWindow('Progman', nil);
  h := FindWindowEx(h, 0, 'SHELLDLL_DefView', nil);
  h := FindWindowEx(h, 0, 'Internet Explorer_Server', nil);
  Result := h <> 0;
end;