(1) In general, for user actions (a_...), ensure that setComputing(false)
is called even if the underlying computing resulted in an exception.
This ensures that the buttons/menu items of the simulator are properly
enabled again and we don't get into a deadlock situation where we
can't even start a new path.
(2) For the automatic step actions, ensure that the path display is
updated even if there is an exception, as there may have been
intermediate steps that had succeeded before the error occurred.
Joachim Klein
0559014a2f