Currently, user interfaces are defined by single applications but workflows may span multiple ones. In the result, users have to work with separated programs in parallel and deal with separated interfaces to fulfill their tasks. In desktop computing with extensive screens, working with several opened windows might not be eligible but bearable. For mobile devices with very restricted interaction capabilities (e. g. scarce screen estate), the limitations of traditional UIs become a barrier. Therefore we argue that not applications but workflows and tasks should be the determinant for the user interface. This paper introduces in the research question about how to identify the user's current task and focuses on how to reorganize user interfaces across multiple concurrently used applications.