Extensible Nautilus Sidebar Panel

This specification proposes an improved sidebar panel in Nautilus that uses different engines (so as to avoid adding dependencies to Nautilus) to display metadata, relevant information about files, and actions that can be performed on them. It could list related docuements (using Tracker or Beagle), allow editing of metadata, show detailed previews of files or add links to relevant web searches or pages in the history - semantically linking all of a user's data together.