Rich text files have groupings of text, where styles are pushed onto
the stack when encountering a start of the group, then popped at the
end of the group.  This was being handled improperly before, because a
single styleChanged flag was being stored to keep track of whether the
style needed to be restored at the end of a group. This fails to work
properly since the single flag isn't keeping track of all the levels
of the stack, so some styles are not restored properly.