Check Syntax blocks DrRacket until finished

[soegaard]

Turn off automatic syntax checking in DrRacket.
Clone Urlang (https://github.com/soegaard/urlang/ )
Open urlang/main.rkt and click the "Check Syntax" button.

https://github.com/soegaard/urlang/blob/master/urlang/main.rkt

The syntax checking takes a long time, but it should only affect that one tab.
Until the syntax checker is finished DrRacket complete blocks. To a degree that
using tab back and forth between DrRacket and a browser window, makes
one believe that DrRacket has crashed.