added this directory with stuff from the tutorial, updated to compile and

Mon Mar 23 12:03:03 CST 1998 Shawn T. Amundson <amundson@gtk.org>

        * examples/: added this directory with stuff from
          the tutorial, updated to compile and work with recent
          changes

examples/helloworld/helloworld.c

@@ -0,0 +1,97 @@
+/* This file extracted from the GTK tutorial. */
+
+/* helloworld.c */
+               
+#include <gtk/gtk.h>
+
+/* this is a callback function. the data arguments are ignored in this example.
+ * More on callbacks below. */  
+void hello (GtkWidget *widget, gpointer data)
+{
+    g_print ("Hello World\n");
+}
+     
+
+gint delete_event(GtkWidget *widget, gpointer data)
+{
+    g_print ("delete event occured\n");
+    /* if you return FALSE in the "delete_event" signal handler,
+     * GTK will emit the "destroy" signal.  Returning TRUE means
+     * you don't want the window to be destroyed.
+     * This is useful for popping up 'are you sure you want to quit ?'
+     * type dialogs. */
+
+    /* Change TRUE to FALSE and the main window will be destroyed with
+     * a "delete_event". */
+
+    return (TRUE);
+}
+
+/* another callback */
+void destroy (GtkWidget *widget, gpointer data)
+{
+    gtk_main_quit ();
+}
+
+int main (int argc, char *argv[])
+{
+    /* GtkWidget is the storage type for widgets */
+    GtkWidget *window;
+    GtkWidget *button;
+
+    /* this is called in all GTK applications.  arguments are parsed from
+     * the command line and are returned to the application. */
+    gtk_init (&argc, &argv);
+    
+    /* create a new window */
+    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+
+    /* when the window is given the "delete_event" signal (this is given
+     * by the window manager (usually the 'close' option, or on the
+     * titlebar), we ask it to call the delete_event () function
+     * as defined above.  The data passed to the callback
+     * function is NULL and is ignored in the callback. */
+    gtk_signal_connect (GTK_OBJECT (window), "delete_event",
+                        GTK_SIGNAL_FUNC (delete_event), NULL);
+
+    /* here we connect the "destroy" event to a signal handler.
+     * This event occurs when we call gtk_widget_destroy() on the window,
+     * or if we return 'TRUE' in the "delete_event" callback. */
+    gtk_signal_connect (GTK_OBJECT (window), "destroy",
+                        GTK_SIGNAL_FUNC (destroy), NULL);
+
+    /* sets the border width of the window. */
+    gtk_container_border_width (GTK_CONTAINER (window), 10);
+
+    /* creates a new button with the label "Hello World". */
+    button = gtk_button_new_with_label ("Hello World");
+
+    /* When the button receives the "clicked" signal, it will call the
+     * function hello() passing it NULL as it's argument.  The hello() 
+     * function is defined above. */
+    gtk_signal_connect (GTK_OBJECT (button), "clicked",
+                        GTK_SIGNAL_FUNC (hello), NULL);
+    
+    /* This will cause the window to be destroyed by calling
+     * gtk_widget_destroy(window) when "clicked".  Again, the destroy
+     * signal could come from here, or the window manager. */
+    gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
+                               GTK_SIGNAL_FUNC (gtk_widget_destroy),
+                               GTK_OBJECT (window));
+                        
+    /* this packs the button into the window (a gtk container). */
+    gtk_container_add (GTK_CONTAINER (window), button);
+    
+    /* the final step is to display this newly created widget... */
+    gtk_widget_show (button);
+
+    /* and the window */
+    gtk_widget_show (window);
+     
+    /* all GTK applications must have a gtk_main().     Control ends here
+     * and waits for an event to occur (like a key press or mouse event). */
+    gtk_main ();
+                        
+    return 0;
+}
+