...turns out ca0600f0 "multiple unsequenced
modifications to 'nPos' [-Werror,-Wunsequenced]" was wrong in assuming that the
order of getPropertyPos had no meaning, as it determines the order in which
form property dialogs display items.

So, reintroduced a fixed order, but without resorting to undefined behavior due
to repeated uses of ++ with no sequence points in between.  This is rather
sluggish, but gets the job done.

Change-Id: If9c5f4130fe6523eebd3a13e5a685fc9c0f53fc0