{
XYPixmap
ZPixmap
XShmGetEventBase :: event code.
XShmGetImage
XShmPixmapFormat(display) == ZPixmap
XShmQueryExtension
}
//XShmQueryVersion(display, @major, @minor, @pixmaps{bool});

{
XCreateSimpleWindow(display, RootWindowOfScreen..., InputOutput, visual); != 0

XSizeHints hints
hints.flags = PSize or PMinSize or PMaxSize;
hints.min_width := hints.max_width := hints.base_width := image_width;
hints.min_height...
XSetWMNormalHints(display, window, &hints);
XStoreName(display, window, "Nice Title");
XSelectInput(display, window, ExposureMask or PKeyPressMask or KeyReleaseMask or ButtonPressMask);

XCreateGC(display, window, 0, NULL) // XPutImage.
}
//XMap{Raised}(display, window);
{
XCreateImage(display, visual, depth, ZPixmap, offset, data, width, height, bitmap_pad, bytes_per_line)

XPutImage(display, drawable, gc, image, src_x, src_y, dest_x, dest_y, width, height)

XFreeGC
XDestroyWindow
XCloseDisplay

XShmPutImage(display, drawable, gc, image, src_x, src_y, dest_x, dest_y, width, height, send_completion_event)
XFlush

}

{
shmget(IPC_PRIVATE, bytes_per_line * height, IPC_CREAT|0666); < 0 error.
addr = shmat(shmid, NULL, 0) == 0 error.
readOnly = False.

...
XShmDetach
XDestroyImage
shmdt
shmctl(shmid, IPC_RMID, NULL);
free seginfo
Free GC
Destroy Window.
Close Display.

// or maybe XSetWindowBackgroundPixmap.

// event loop:

// XNextEvent(display, &ev);
// ev.type == KeyPress || ButtonPress.
// XNextPevent flush the output buffer?
// key codes: XK_Escape, ...
}