After Gecko 2.0, the version number was bumped to 5.0 to match Firefox 5, and from then on has been kept in sync with the major version number for both Firefox and Thunderbird, to reflect the fact that it is no longer a separate component.
Posle Gecko-a 2.0, broj verzije je podignut na 5.0 da odgovara Firefox-u 5 i od tada je sinhronizovan sa verzijama Firefox-a i Thunderbird-a, da odražava činjenicu da nije više odvojena komponenta.