function startImageSlideshow () {
	if (!document.getElementsByTagName) return;
	var all_images = document.getElementsByTagName("img");
	var images = [];
	for (var i = 0; i < all_images.length; ++i) {
		var image = all_images[i];
		if (!image.className) continue;
		if (/(^|\s)image_slideshow(\s|$)/.test(image.className)) {
			images.push(image);
		}
	}
	if (!images.length) return;
	var image_index = 0;
	window.setInterval(function () {
		image_index++;
		if (image_index >= images.length) {
			image_index = 0;
		}
		for (var i = 0; i < images.length; ++i) {
			if (i == image_index) {
				images[i].style.display = "inline";
			} else {
				images[i].style.display = "none";
			}
		}
	}, 2000);
}