pfontdesc:Merge(desc_to_merge, replace_existing)
desc_to_merge into the fields in
the font description.
If replace_existing is False, only fields in the font description that
are not already set are affected. If True, then fields that are
already set will be replaced as well.
True, replace fields in the font description with the corresponding values from desc_to_merge, even if they are already exist.