I created a new User assigned to the Demo-project-publishers group. When loging in the admin central, the demo-project is mark as readonly (ok). When opening the demo-project, the edit bars are accessible (can open the component property or start to add a component). Once we try to save the modifications we got the following exception (Ok)

2012-03-13 14:44:14,624 ERROR nfo.magnolia.module.admininterface.SaveHandlerImpl: /demo-project/content/0/MetaData/mgnl:authorid: not allowed to add or modify item
javax.jcr.AccessDeniedException: /demo-project/content/0/MetaData/mgnl:authorid: not allowed to add or modify item

Edit bar should not appear on read-Only users!