Initialization

First, GTK+ must be initialized:

  gtk_init(&argc, &argv);

This call connects to an X server, and parses some default arguments understood by all GTK+ programs. Parsed arguments are removed from argv, and argc is decremented accordingly. gtk_init() also registers a "cleanup function" using atexit(). In practice, this is only important when you fork(); the child process must exit with _exit() rather than exit() to avoid shutting down GTK+ in the parent.