You can call this on a source that has been destroyed, provided
that the glib.MainContext it was attached to still exists (in which
case it will return that glib.MainContext). In particular, you can
always call this function on the source returned from
g_main_current_source(). But calling this function on a source
whose glib.MainContext has been destroyed is an error.
Gets the glib.MainContext with which the source is associated.
You can call this on a source that has been destroyed, provided that the glib.MainContext it was attached to still exists (in which case it will return that glib.MainContext). In particular, you can always call this function on the source returned from g_main_current_source(). But calling this function on a source whose glib.MainContext has been destroyed is an error.