addCustomEventHandler("hide_all_pictures", function() {
changeVisibility("ImageBox_1", 0, false);
changeVisibility("ImageBox_2", 0, false);
changeVisibility("ImageBox_3", 0, false);
changeVisibility("ImageBox_4", 0, false);
changeBgColor("TextBox_1", "#FFFFFF");
changeBgColor("TextBox_2", "#FFFFFF");
changeBgColor("TextBox_3", "#FFFFFF");
changeBgColor("TextBox_4", "#FFFFFF");

});