#include <stdio.h>#include <stdlib.h>#include <string.h>#include <minigui/common.h>#include <minigui/minigui.h>#include <minigui/gdi.h>#include <minigui/window.h>#include <minigui/control.h>void trackbar_demo (HWND hwnd){    MessageBox (hwnd, "Sorry, this demo is under construction!",                    "Under construction!", MB_OK | MB_ICONINFORMATION);}