IDispatcherScheduler interface

Created by CreateDispatcherScheduler on that thread, which it is bound to. The scheduler has no threads; the event loop drives it. A task starts with RunTask, typically from an event handler, and runs at once until it ends or waits. When a waiting task can go on (ResumeTask, AddTask, a timer), the scheduler hands it to the loop through the DispatcherWakeProc, and the loop passes it to ContinueTask. The bound thread stays an ordinary thread: only the tasks can wait. A task always returns to whoever entered it last, so handlers that start or continue tasks get control back before they return themselves; tasks may also be started or continued from within other tasks and from modal loops inside them. Start does nothing. Stop and Destroy are called once no task waits or is on its way to the loop; Stop on the bound thread.