shortcircuit some of the code involved in  drawing the margin highlight
for online expansion errors

This avoids drawing the margin highlight when it isn't inside the
region being repainted and it avoids even figuring anything out about it
when there is currently no error range

NOT for the release branch
fix improper fraction display

closes PR 13558

please include in the release
fix test suite to match earlier fix to obligation info

merge to release branch, please