function setDisplay(call, obj) {
  var obj = document.getElementById(obj);
  var disp = obj.style.display;
  if (disp == 'none') {
    obj.style.display = 'block';
    call.removeChild(call.firstChild);
    call.appendChild(document.createTextNode("–"));
  } else {
    obj.style.display = 'none';
		call.removeChild(call.firstChild);
    call.appendChild(document.createTextNode("+"));
  }
  if (disp == 'none') {
    obj.style.display = 'block';
    call.removeChild(call.firstChild);
    call.appendChild(document.createTextNode("–"));
  }
}