Unity8 is a very important part of the Ubuntu infrastructure and it's being improved on a constant basis. A new major update has landed, bringing some interesting new features.
Mark Shuttleworth was asked what the most interesting new feature for Ubuntu Touch was, and he said it was a piece of code that hasn't landed yet, which improved the right click navigations a great deal.
The latest release notes for Unity8 UI show that that particular feature, which sounds really exciting, is getting close to a release, along with a few other ones.
According to Kevin Gun, a lead developer for Unity8 and Mir, copy-paste functionality has been added, the right-edge navigation feature got a number of improvements, and a lot of dash layout work has been implemented.
Also, Mir has been updated to version 0.1.5, Mesa is still being tested, and a number of performance improvements for Mir have been implemented.
Check the official changelog for more details about the latest improvements for Mir and Unity8.