// Switch a tree branch from opened to closed or vice versa
function treeChange(branchName, imageName)
{
	// Open/close branch
	var branch = document.getElementById(branchName).style;
	if ("block" == branch.display) branch.display = "none";
	else branch.display = "block";
	
	// Toggle image
	img = document.getElementById(imageName);
	if (img.src.indexOf(imgPlus.src) > -1) img.src = imgMinus.src;
	else img.src = imgPlus.src;
}