Xtra - An X toolkit extension for handling events asynchronously

Using the X Toolkit Intrinsics and toolkits based upon them, it is possible to create interactive programs in an event driven user interface model. User input events are dispatched to interaction objects ("widgets") whose behaviour consist mainly of single, short reactions to these user input stimuli. Given this model, it is much more difficult to create programs running continuous display operations or doing lengthy computations in the background and have these programs at the same time react on input events as they occure. Checking for input events once in a while in a loop is not very elegant, and in some situations, e.g. while doing database accesses using third party software, it may not be feasible at all. Xtra (X Toolkit Running Asynchronously) is an extension to the X Toolkit Intrinsics. It offers a mechanism to asynchronously dispatch events as they arrive from the X server process. Using Xtra, many dynamic interactive programs can be structured more simply, as the main progra m thread is seperated from the process of gathering and dispatching events. The Xtra extension can be used with any toolkit based on the X Toolkit intrinsics, such as the Athena widget set or the OSF/Motif widgets.