https://roadmap.urbit.org/project/ui-research-beta
HEIGHT 420
View project on Github 
This stage of the research involves writing a renderer to convert hoon UI to a single page application running in the browser. This has various sub-tasks as it is the first time that the hoon UI datastructure will be making the leap to unconstrained 2D graphics. Sub-tasks: JSON conversion Algorithms for laying out arbitrary hoon UI nodes in 2D space
Standardisation of supported marks for the %value attribute
Deeper specifications of the "component jets" idea
Dealing with a client/server split, including optimistic mutations, handling network fetching
It is expected that the spec will be reasonably final by the time that this stage is finished.