// toggles div display and plus/minus sign images

function toggleDisplay(trid, imgid) {
	var objDiv = document.getElementById(trid);
	var objImg = document.getElementById(imgid);	
	if (objDiv.style.display=="none") {
		objDiv.style.display="";
		objImg.src="images/minus.gif";
	} else {
		objDiv.style.display="none";
		objImg.src="images/plus.gif";
	}
}