Updating an operational system is often complex and awkward. In this article, we will explain how the concept of multi-layer interface could facilitate the evolution of operational interactive systems. We will explain how the division in several layers could increase the application acceptance and smooth out learning phases. Furthermore, we will present how we implement this concept in the ASTER project. Keywords Multi-layer interface, direct manipulation, working method evolution. ACM Classification Keywords D.2.2 [Design Tools and Techniques] : User interfaces; H.5.2 [User Interfaces] : Interaction styles;