var openImg = new Image();
openImg.src = "/images/base.gif";
var closedImg = new Image();
closedImg.src = "/images/folder.gif";
var plusImg = new Image();
plusImg.src = "/images/plus.gif";
var minusImg = new Image();
minusImg.src = "/images/minus.gif";

function showBranch(branch){
	var objBranch = document.getElementById(branch).style;
	if(objBranch.display=="block") {
		objBranch.display="none";
		swapFolder('I' + branch);
	}
	else {
		objBranch.display="block";
		swapFolder('I' + branch);
	}
}

function showChapter(chapter){
	var objChapter = document.getElementById(chapter).style;
	objImg = document.getElementById('I' + chapter);
	if(objImg.src.indexOf(openImg.src)>-1) {
		objChapter.display="none";
		swapFolder('I' + chapter);
		}
	else {
		objChapter.display="block";
		swapFolder('I' + chapter);
	}
}

function swapFolder(img){
	objImg = document.getElementById(img);
	objSignImg = document.getElementById(img + 'sign');
	if(objImg.src.indexOf(closedImg.src)>-1){
		objImg.src = openImg.src;
		objSignImg.src = minusImg.src;
		}
	else {
		objImg.src = closedImg.src;
		objSignImg.src = plusImg.src;
	}
}