The "parent" group changed iff this is the first iteration of *this*
group *or* *detail* *section*.

The "parent" group's first iteration means that we are in the first
value of the parent group (in other words, the *grand*-*parent* group
changed).

Change-Id: Ia4a798cb37db2f17e7deef1058b25795bfc02648
Reviewed-on: https://gerrit.libreoffice.org/9503Reviewed-by: Lionel Elie Mamane <lionel@mamane.lu>
Tested-by: Lionel Elie Mamane <lionel@mamane.lu>