Changes

* Do we know status on Retained Layers, when we think it'll be available? We need it for the extension bar + app tabs UI. What we’re trying The UI team would like to accomplish for context:  * [http://newdefaults3.amazonaws.com/data.tumblr.com/post/675679769/tumblr_l3omnrxMAx1qbpfg9o1_1280.png?AWSAccessKeyId=0RYTHV9YYQ4W5Q3HQMG2&Expires=1276712077&Signature=LuRrYmA0udTN9cXiTiArxxM%2Bpb8%3D do something like this]** jdrew thinks this-mockup-shows-is {{bug|130078}} which is a b1 blocker** roc says that-the-status-bar-by-defaulthe thinks that will work, but not sure if requirements have changed** '''limi''' and '''faaborg''' to get in touch with '''roc''' and '''jdrew''' and follow up offline and work through requirements