Retrieves a comment above @key from @group_name.
If @key is %NULL then @comment will be read from above
@group_name. If both @key and @group_name are %NULL, then
@comment will be read from above the first group in the file.
Note that the returned string does not include the '#' comment markers,
but does include any whitespace after them (on each line). It includes
the line breaks between lines, but does not include the final line break.
Retrieves a comment above @key from @group_name. If @key is %NULL then @comment will be read from above @group_name. If both @key and @group_name are %NULL, then @comment will be read from above the first group in the file.
Note that the returned string does not include the '#' comment markers, but does include any whitespace after them (on each line). It includes the line breaks between lines, but does not include the final line break.