Techniques for facilitating secure application interoperation via user interface (UI) gestures in computing devices that strictly isolate applications operating thereon are described herein. For instance, applications may define one or more specific UI gestures that, when executed by the user, express that the user desires for the computing device to allow for an instance of directed, ephemeral, by-value communication between two isolated applications. In some implementations, the gesture is an atomic gesture, such as a drag-and-drop operation. That is, the gesture is one that the user completes continuously and without interruption.