Operator inattention is an important and unsolved problem in mission critical multi-display systems where a single or a group of operators continuously monitor information flows on distributed displays. In this paper we present a novel system solution to this problem and a middleware for supporting flexible attention-aware applications for a variety of domains. Some of the most significant functionality includes direct querying of the application’s attention state, custom callback definitions to be executed on specific attention events or application updates, inter-application message routing, and pushing custom notification with relative location information to any other registered application. We evaluate our middleware by developing three applications that both demonstrate the efficacy and versatility of the system and provide performance estimates in terms of latency as a function of payload size.