12 Startup Actions

The racket/gui/base module can be instantiated only once per operating-system process, because it sets hooks in the Racket run-time system to coordinate between Racket thread scheduling and GUI events. Attempting to instantiate it a second time results in an exception. Furthermore, on Mac OS, the sole instantiation of racket/gui/base must be in the process’s original place.

Instantiating racket/gui/base sets two parameters:

The thread where racket/gui/base is instantiated also becomes the handler thread for the initial eventspace. See also Eventspaces and Threads.