Thanks to the hyperconnected world in which we live, we are surrounded by devices. Many of these devices can communicate with each other, and even they can support the same application so that the user can have multiple forms of interaction. However, developers should be careful when considering the control level left to users, since the applications may become unusable. Whether the system or user decides the distribution of the available devices, Graphical User Interface (GUI) consistency must always be preserved. Consistency not only provides users with a robust framework in similar contexts but is an essential learning element and a lever to ensure the GUI efficient usage. This paper proposes a set of consistency guidelines that serve as a means for the construction of multi-device applications. As a case study, DistroPaint was evaluated by experts who identified consistency violations and assessed their severity.