window for little vGL

void window_demo(void)
{
    /*Create a window*/
    lv_obj_t* win = lv_win_create(lv_scr_act(), NULL);
    lv_win_set_title(win, "Window tille");

    /*Add control button to the header*/
    lv_obj_t* close_btn = lv_win_add_btn(win, LV_SYMBOL_CLOSE);
    lv_obj_set_event_cb(close_btn, lv_win_close_event_cb);
    lv_win_add_btn(win, LV_SYMBOL_SETTINGS);

    /*Add some dummy content*/
    lv_obj_t* txt = lv_label_create(win, NULL);
    lv_label_set_text(txt, "This is the content of the window\n\n"
        "You can add control buttons to\n\n" 
        "the window header\n\n"
        "The content area becomes automatically\n\n"
        "scrollable is it's large enough.\n\n" 
        " You can scroll the content\n\n" 
        "See the scroll bar on the right!");

}