This header is used by Component Object Model (COM). For more information, see:
messagedispatcherapi.h contains the following programming interfaces:
Called by message dispatchers on an ASTA thread after dispatching a windows message to provide an opportunity for short-running infrastructural COM calls and other high-priority or short-running COM work to be dispatched between messages.
Registers or unregisters the per-thread message dispatcher that is to be invoked when there are window messages available to dispatch within COM wait APIs on an ASTA thread.