function change_menu_img(j, on) {
	if(document.getElementById('menu_img_off_' + j).innerHTML==' ') {
		document.getElementById('menu_img_off_' + j).innerHTML = document.getElementById('menu_img_' + j).src;
	}
	
	if(on==1) {
		document.getElementById('menu_img_' + j).src = document.getElementById('menu_img_on_' + j).innerHTML;
	}
	else {
		document.getElementById('menu_img_' + j).src = document.getElementById('menu_img_off_' + j).innerHTML;
	}
}