C-GTK helloworld

#include <gtk/gtk.h>

static void
print_hello (GtkWidget *widget,
             gpointer   data)
{
    g_print ("Hello World\n");
}

static void
activate (GtkApplication *app,
          gpointer        user_data)
{
    GtkWidget *window;
    GtkWidget *button;
    GtkWidget *box;

    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), "Window");
    gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);

    box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
    gtk_widget_set_halign (box, GTK_ALIGN_CENTER);
    gtk_widget_set_valign (box, GTK_ALIGN_CENTER);

    gtk_window_set_child (GTK_WINDOW (window), box);

    button = gtk_button_new_with_label ("Hello World");

    g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);
    g_signal_connect_swapped (button, "clicked", G_CALLBACK (gtk_window_destroy), window);

    gtk_box_append (GTK_BOX (box), button);

    gtk_widget_show (window);
}

int
main (int    argc,
      char **argv)
{
    GtkApplication *app;
    int status;

    app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
    g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
    status = g_application_run (G_APPLICATION (app), argc, argv);
    g_object_unref (app);

    return status;
}