level of detail. Further, jointly viewing of content such as photos is limited to a small number of users. In contrast, users find large displays in their environments yet cannot make use of them by exploiting the available screen space. For instance, public displays at airports or train stations, TV sets, or information kiosks can be found in many situations and users’ environments. In this paper, we present an approach which allows users to establish an ad-hoc connection between their mobile devices and external displays by holding the phone on the border of an external screen (see Figure 1(a) and (b)) in order to temporarily extend the mobile user interface across the mobile and the external screen. This allows users to take advantage of existing large displays in their environments through spanning the mobile application user interface across multipledisplayswhichallowstodisplaymoreinformationatonce(see Figure1(b)and(c)). Inaddition,multipleuserscantakeadvantage of an external screen as a shared interactive surface that allows for instance, sharing and transferring data from one device to another (see Figure 1(d)).