function swapCategoryDisplay (index) {
	if (!document.getElementById) return;
	for (var i = 1; i <= 20; i++) {
		if (i == index || !index) {
			var bool = (document.getElementById ("categoryBlock" + i).style.display != "none");
			document.getElementById ("categoryBlock" + i).style.display = bool ? "none" : "block";
			changeImage ("categoryListMarker" + i, "/shabake/book/index/images/listmarker_" + (bool ? "plus" : "minus") + ".jpg");
			deleteRestoreImage ("categoryListMarker" + i);
		}
	}
}
if (document.getElementById) {
	addWindowListener ("load", swapCategoryDisplay);
}