A Multi-target user interface is composed of a series of interconnected variations of the same user interfaces, but tailored for different targets or different contexts of use. When access to software applications must be guaranteed in more than one context of use, it is necessary to adapt these user interfaces in order to preserve their usability when the switch between contexts occur. For this purpose, this paper proposes a model and a presentation technique to express and manipulate the plasticity domain of a user interface. The plasticity domain denotes the set of contexts of use it is able to cover while preserving its usability. In this paper, we focus on one aspect of the context of use: the platform screen size. A window requires a graphical area for its rendering and manipulation by the enduser. The model supports the definition of this graphical area in terms of window size and window place. The visualization technique helps in both making observable the set of presentations...