Variability management supporting the model-driven design of user interfaces

User Interfaces (UI) design is a complex and multi-faceted problem. It depends on devices, users and their environments and involves various stakeholders with different backgrounds. Moreover, user requirements are difficult to evaluate precisely upfront and require iterative design cycles based on trial and error. All this variability is complex and should be managed efficiently to ensure moderate design costs. One solution is to implement in the UI design process Model-Driven Engineering (MDE) and Software Product Lines (SPL). However, current SPL approaches do not consider problems related to specific UI design models, notably the many concerns underlying them. We propose an SPL approach that supports the separation of concerns through multi-step partial configuration of UI features. The approach is implemented in our existing MDE UI generation framework.