file-drawer: This is the old code which uses a NSDrawer attached to the window. But this does not work with fullscreen mode, hence this branch is deprecated. It can still be used as a more ‘stable’ version of the whole project, because the new split-browser branch might contain other bugs related to changing the way the window deals with its views.
split-browser: This branch replaces the drawer with a sidebar and is where ongoing development will happen. It might be a teeny bit less ‘stable’ than the file-drawer branch, but daily usage should be possible and is encouraged. Please file tickets for any issue you might come across.