As of Zip 2000, an optimisation has been applied: the Z-machine program
counter, stack pointer and frame pointer are help in ARM registers (v6,
v5, v4 respectively). This is declared in globalregs.h.

There is danger in this, in that libraries do not know about this usage.
It is safe for libraries that are simply called then return, as they
will preserve all the variable registers. However, any library routines
that call you back through a function pointer (eg bsearch) may call
you with fp, sp and pc effectively corrupt.

To make the event dispatching work, you will need to create a version of
OSLibSupport with knowledge of the global registers. The easiest way
to do this is to #include "globalregs.h" at the top of Event.h.

Beware. Here be dragons.

Don't try this at home, kids.

If you have any problems, comment out the contents of globalregs.h.