A way to allow to all authentificate user to read all groups contents ?

Hello,

Is there a way in OG to allow to all the authentificate Users to read each group content even if they are not member.

Only member can write in thier groups.

I mean instead of having just Public / Private group visibility I'd like to have a third option : readonly for non-members.

Sorry for my hazardous english and Thanks for all the work.
:-)

Did