I'm using Drupal 7 and Organic Groups along with a number of popular contributed modules. My situation:
I have a group called 'Project'. There are multiple group roles that have access to this group; 'administrator', 'client' and 'contractor'.
There is also a group content node called 'invoice' targetted to the 'Project' group node. How can I restrict a user from viewing invoice nodes that has been assigned the group role 'contractor'? I don't want to manage this through the User Permissions as a user may have different access rights to different projects, hence the requirement for viewing group content managed via OG roles.