Jerome Vouillon writes:
 > There is a mutex that prevents two Caml threads from running
 > simultaneously.  I think what happens is that the Tk main loop
 > blocks while still holding the mutex.
 > You should try to release the mutex before entering this loop, and
 > acquire it again before each call to a Caml function. For instance,
 > in file cltkEvents.c:
 > ...

Nice idea, but it it didn't work for me, so there must be something
else wrong ...