General
Each screen should use the same interaction scheme and follow the same layout guidelines so that users get used to the interface quickly. Absolute positioning of widgets should be avoided to allow different styles to be applied easily without messing up the whole layout.
The user interface should consist of static, non-changing screens, one for each action and interaction type, which can be switched via certain pre-defined buttons by the user. It uses an hierarchical structure, which will guide the user back to the previous (parent) screen once he wants to leave the current one.
