• Upgrade to new @phosphor packages - brings a new Command Palette interaction that should be more intuitive, and restores the ability to drag to dock panel edges #1762.
• Refactor of RenderMime and associated renders to use live models. See #1709 and #1763.
• Improvements and bug fixes for the completer widget: #1778
• Upgrade CodeMirror to 5.23: #1764
• Numerous style updates and bug fixes.