As the cost of display hardware falls so the number of public display networks being deployed is increasing rapidly. While these networks have traditionally taken the form of digital signage used for advertising and information there is increasing interest in the vision of "open display networks". A key component of any open display network is an effective channel for disseminating applications created by third-parties and recent research has proposed a display-oriented "application store" as one such channel [5]. In this paper we present a critical analysis of the requirements and design of display application stores -- providing insights designed to help the implementers of future application stores.