nt loop would normally run in the thread with which the program
started.  This procedure is not thread safe - if it might be called by
a different thread from others which might access the default event
loop, then external synchronization may be required.  However, that
should not normally be an issue.  The normal course would be to call
this procedure once only on program start up, before other threads
have started.  It is usually a mistake to call this procedure twice:
if there are asynchronous events pen