Today’s mobile phones enable users to perform all kinds of tasks while being on the go. For instance, users can edit photos, movies, or text documents as well as performing many other complex tasks. One of the main limiting factors is the size of the mobile phone screen. It allows only a small number of items to be displayed at once [1]. Hence, only few information and details can be displayed on one application page. Therefore, users often have to switch be- tween different pages or views to access different pieces of information or resize content such as maps or images to view the needed 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 inter- face 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 multiple displays which allows to display more information at once (see Figure 1(b) and (c)). In addition, multiple users can take advantage 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)).