The UI Framework module introduces a custom user interface framework built on top of Spring MVC that will be the basis of the OpenMRS 2.x web application, and can also be used in OpenMRS 1.8.4+.
Note that the major version numbers of the UI Framework module are significant, and each major version upgrade (1.x, 2.x, 3.x, etc) introduces backwards-incompatible changes. See Backwards-Compatibility across UI Framework major versions.
Note that this module provides only a framework and no real content. The UI Commons module provides reusable UI content.