Typically, the bluebox table includes keys that have interned parts,
so serialization can save space both on disk and in memory when the
bluebox information is reloaded.
when the blue box doesn't fit in the visible region
in one direction (either x or y) but does fit
in the other region, then it was being drawn in
the wrong place
This code is still sub-optimal, since it isn't leaving
space for the words underneath the lock in the case
the lock is near the bottom of the visible region, but
it seems better to just let that be invisible rather
than make the lock float a bit in that case.
closes PR 13142
is no bluebox information, then we can just bypass updating
it on insertions (especially important when loading a big
file into drracket, as there is a lot of insertion but no
blue boxes (yet))
