Occurs periodically when the link is blocking in a reading call.
In a single-threaded program, a handler for the Yield event can be used as a place to perform actions necessary to keep the program responsive (like calling Application.DoEvents()). For most programs, a better choice is to use multiple threads, so that your user interface thread is not blocked waiting for the result of a Mathematica computation.The Yield handler is passed no arguments. It should return true or false to indicate whether to back out of the read call or not. Returning true means to back out, which will cause a MathLinkException to be thrown in the Get call that is currently blocked waiting for data.