Synchronous vs. asynchronous mode:  On X Window, a request sent to the server is not immediately processed even if the function returns. It is processed only after it returns to the main loop. For example, a request for displaying a view is performed only when the X Window server sends back a map notify event and this event is processed by the Rogue Wave Views API.

Timers management:  On Microsoft Windows, a timer notification is a Windows event that can be processed in the event loop. On X Window, a timer notification is not an event and therefore the main loop is not aware of it, whether it is active or not.