#include <X11/Xlib.h>
#include <X11/extensions/Xcomposite.h>
#include <stdlib.h>
#include <stdio.h>

static int comp_event;
static int comp_error;

/* This program shows that calling XCompositeUnredirect() on a window
 * will cause underlying _redirected_ windows to be exposed.
 */
static void
disaster (const char *what)
{
    fprintf (stderr, "Error: %s\n", what);
    exit (0);
}

static char *
get_event_name (int type)
{
    if (type == Expose)
	return "Expose";
    else
	return "Unknown event type";
}

static void
dump_events (Display *dpy, const char *header)
{
    XSync (dpy, False);
    
    if (header)
	printf ("%s", header);
    
    while (XPending (dpy))
    {
	XEvent event;
	
	XNextEvent (dpy, &event);

	if (header)
	{
	    printf ("  event: %s  (%lx)\n",
		    get_event_name (event.type), event.xany.window);
	}
    }
}
    
int
main (int argc, char **argv)
{
    Display *dpy;
    Window main_window;
    Window redirected_window;
    Window non_redirected_window;

    dpy = XOpenDisplay (NULL);
    if (!XCompositeQueryExtension (dpy, &comp_event, &comp_error))
	disaster ("No composite extension found\n");

    /* Create main window */
    
    main_window = XCreateSimpleWindow (dpy, XDefaultRootWindow (dpy),
				       100, 100, 600, 400, 0, 0, 0xffffffff);
    XMapWindow (dpy, main_window);

    XCompositeRedirectSubwindows (dpy,
				  main_window,
				  CompositeRedirectManual);
    
    /* Create redirected subwindow */

    redirected_window = XCreateSimpleWindow (dpy, main_window,
					     50, 50, 500, 300,
					     0, 0, 0x000000ff);
    printf ("redirected window is %lx\n", redirected_window); 
    XSelectInput (dpy, redirected_window, ExposureMask);
    XMapWindow (dpy, redirected_window);

    /* discard all events resulting from the map */
    dump_events (dpy, NULL);

    /* Create unredirected subwindow, completely covering
     * the redirected one
     */
    non_redirected_window = XCreateSimpleWindow (dpy, main_window,
						 25, 25, 550, 350,
						 0, 0, 0xaaaaaaaa);
    XMapWindow (dpy, non_redirected_window);

    /* discard all events resulting from the map */
    dump_events (dpy, NULL);

    XCompositeUnredirectWindow (dpy, non_redirected_window,
				CompositeRedirectManual);

    dump_events (dpy, "events caused by unredirecting\n");

    sleep (100);
}