function toggleCollapse(elementName)
{
	var element = document.getElementById(elementName);
	
	if (element == null)						//no such element
		return;
		
	if (element.style.display == "none")		//element is collapsed
		element.style.display = "block";
	else 										//element is expanded
		element.style.display = "none";
		
	element = document.getElementById(elementName + "_icon");

	if (element == null)						//no such element
		return;
		
	if (element.innerHTML == "+")				//element is collapsed
		element.innerHTML = "-";
	else 										//element is expanded
		element.innerHTML = "+";
}