The software development process of user interfaces for complex control system can constantly change in requirements. In those systems changes are costly (time consuming) and error prone, since we must guarantee that the resulting system implementation will still be robust and reliable. A way to tackle this problem is to bring a software model based approach for specification and providing at the same time rapid prototyping capabilities (to speed up design) and Simulation/Verification capabilities (to assure quality). We propose a full model-based methodology to guide designers through specification changes.As a validation case study we have chosen a real life problem: the ATLAS Online Software framework, which has the main purpose to provide a stable software development platform for managing both trigger and data-acquisition processes. In this paper, we explain how to describe a particular control system: the ATLAS Trigger-DAQ system and its graphical user interface (GUI), and we wiD describe how we can validate such specifications, by means of automatic verification techniques like simulation and model checking or testing.