* applications this is the always the current instance.
* On Linux, the D-Bus session bus is used for communication.
*
+ * The use of #GApplication differs from some other commonly-used
+ * uniqueness libraries (such as libunique) in important ways. The
+ * application is not expected to manually register itself and check if
+ * it is the primary instance. Instead, the <code>main()</code>
+ * function of a #GApplication should do very little more than
+ * instantiating the application instance, possibly connecting signal
+ * handlers, then calling g_application_run(). All checks for
+ * uniqueness are done internally. If the application is the primary
+ * instance then the startup signal is emitted and the mainloop runs.
+ * If the application is not the primary instance then a signal is sent
+ * to the primary instance and g_application_run() promptly returns.
+ * See the code examples below.
+ *
* If used, the expected form of an application identifier is very close
* to that of of a
* <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-interface">DBus bus name</ulink>.