My first app in GDK library

my_first_gdk_app.c

/* 
 * Adopted from http://james.id.au/tech/doc/gdk/
 * gcc -o my_first_gdk_app.bin my_first_gdk_app.c `pkg-config gtk+-2.0 --cflags --libs`
 * The GDK headers. Very important.
 */
#include <gdk/gdk.h>

/* Convenient way to suck in all the glib stuff.
 */
#include <glib.h>

int main (int argc, char *argv[]) {
    /* a pointer to a window object - this is what we will draw on.
     */
    GdkWindow *window;

    /* a set of "attributes" for our windows. This struct holds things
     * like width, height etc.
     */
    GdkWindowAttr attributes;

    /* a bitmask of the attributes you actually want to read out of the
     * attributes thing above
     */
    gint attributes_mask;

    /* GDK apps need a main loop to wait for events and so forth. This main
     * loop has a struct which tells you about it called "GMainLoop". We need
     * one of them.
     */
    GMainLoop *mainloop;

    /* initialise gdk. We pass in argc and argv - it uses them for info like
     * display on X and so forth. Die if GDK can't initialize.
     * 
     * Always initialise gdk before working with it. Stuff breaks otherwise.
     */
    if (!gdk_init_check (&argc, &argv)) {
        return FALSE;
    }

    /* gdk_rgb_init() is a function which I can only guess sets up the
     * true colour colour map. It returns void so we can't check its
     * return value.
     */
    gdk_rgb_init();

    /* set the attributes for the window. Lets create a 400x400 top-level
     * window.
     */
    attributes.window_type = GDK_WINDOW_TOPLEVEL;
    attributes.width = 400;
    attributes.height = 400;
    attributes.wclass = GDK_INPUT_OUTPUT;

    /* Get a true-colour colour map. GDK also supports indexed colour maps
     * but they aren't so interesting for us.
     */
    attributes.colormap = gdk_rgb_get_cmap ();

    /* set our mask so that the "colormap" element is used.
     */
    attributes_mask = GDK_WA_COLORMAP;

    /* create the window.
     */
    window = gdk_window_new (NULL, &attributes, attributes_mask);

    /* show the window.
     */
    gdk_window_show (window);

    /* Create a new main loop object. The True is to say that the structure
     * should be initialised to say that it is running.
     */
    mainloop = g_main_new (TRUE);

    /* Run that main loop
     */
    g_main_run (mainloop);
}