Abstract: Systems and approaches enable concurrent interaction with multiple user applications in a multi-tasking environment. User input, such as voice commands, head movement, hand or finger gestures, device motion, can be received to a centralized component of a system. State information for each user application can be determined, and the centralized component can send a recognized command or gesture to the appropriate user application(s) based on the state information and/or rules for propagating user input. Additionally, users can configure the input modalities of each user application to customize interaction with systems.