Returns the values associated with key under group_name.
In the event the key cannot be found, NULL is returned and
error is set to G_KEY_FILE_ERROR_KEY_NOT_FOUND. In the
event that the group_name cannot be found, NULL is returned
and error is set to G_KEY_FILE_ERROR_GROUP_NOT_FOUND.
Since 2.6
Returns the values associated with key under group_name. In the event the key cannot be found, NULL is returned and error is set to G_KEY_FILE_ERROR_KEY_NOT_FOUND. In the event that the group_name cannot be found, NULL is returned and error is set to G_KEY_FILE_ERROR_GROUP_NOT_FOUND. Since 2.6