In order to enrich information displayed by GApplication command line
handling when --help is invoked, 3 new methods are proposed:
. g_application_set_option_context_parameter_string
. g_application_set_option_context_summary
. g_application_set_option_context_description
Those methods interact with the GApplication's internal GOptionContext
which is created for command line parsing in g_application_parse_command_line.
(please refer to the GOptionContext class for more information about option
context, parameter string, summary and description.)
To illustrate the 3 methods, an example is provided:
. gapplication-example-cmdline4.c
