Merges the fields that are set in desc_to_merge into the fields in
desc, without copying allocated fields.
This is like pango.font_description.FontDescription.merge, but only a shallow copy
is made of the family name and other allocated fields. desc can only
be used until desc_to_merge is modified or freed. This is meant to
be used when the merged font description is only needed temporarily.
Merges the fields that are set in desc_to_merge into the fields in desc, without copying allocated fields.
This is like pango.font_description.FontDescription.merge, but only a shallow copy is made of the family name and other allocated fields. desc can only be used until desc_to_merge is modified or freed. This is meant to be used when the merged font description is only needed temporarily.