Refreshing Linux Group Rights

Maybe I'm mistaken, but I think there is no other way to let your system know that you e.g. are now member of another group than logging out and back in. And I'm wondering - why? Can it be so complicated? We can reload, refresh everything, but for that you'd have to log out, which is especially annoying in X...

But that' wrong! You can work around the problem with newgrp. The program updates the environment variables so you can immediately use the group, at least in the shell started via newgrp.