Adds a string to be displayed in --help output before the list of options. This is typically a summary of the program functionality. Note that the summary is translated (see set_translate_func(), set_translation_domain()). Since: 2.14 a string to be shown in --help output before the list of options Returns: the summary See set_summary() for more information the summary Since: 2.14 Adds a string to be displayed in --help output after the list of options. This text often includes a bug reporting address. Note that the summary is translated (see set_translate_func()). Since: 2.14 a string to be shown in --help output after the list of options Returns: the description See set_description() for more information the description Since: 2.14 A convenience function to use gettext() for translating user-visible strings. Since: 2.14 the domain to use Return value: the value associated with the key as a double, or a #GKeyFile a group name a key return location for a #GError the value associated with the key as a double, or 0.0 if the key was not found or could not be parsed. Since: 2.14 Associates a new double value with @key under @group_name. If @key cannot be found then it is created. Since: 2.14 a #GKeyFile a group name a key an double value