1. A system for sharing a physical display screen among multiple applications on a mobile platform, comprising: an Internet-connected client device; and software executing on the client device from a non-transitory physical medium, the software providing: a first function assigning dominancy to one of the multiple running applications; a second function mitigating application background transparency among the multiple running applications; a third function establishing a messaging mechanism and protocol between the multiple running applications; and a fourth function enabling the dominant application to intercept digital input directed toward individual ones of the multiple running applications and to dispatch the input to the appropriate application.