function checkBoxes() {
	for (i=1; i<=7; i++) {
	  e = document.getElementById("th" + i);
	  if (e && e.value == "th" + i)
	    turnOnOnly(i);
	}
      }

function selectAll() {
  for (i=1; i<=7; i++) {
     turnOnOnly(i);
     s = 'th' + i;
     v = document.getElementById(s);
     if (v)
        v.value = s;
   }
   f = document.getElementById("timelineForm");
   f.submit();
}

function selectNone() {
  for (i=1; i<=7; i++) {
     turnOffOnly(i);
     s = 'th' + i;
     v = document.getElementById(s);
     if (v)
        v.value = "";
   }
   f = document.getElementById("timelineForm");
   f.submit();
}

function turnOffOnly(x) {
      d = document.getElementById("on" + x);
      if (d) d.style.display = "none";
      d = document.getElementById("off" + x);
      if (d) d.style.display = "block";
      }

function turnOnOnly(x) {
      d = document.getElementById("on" + x);
      if (d)
        d.style.display = "block";
      d = document.getElementById("off" + x);
      if (d)
  	d.style.display = "none";
      }

function turnOff(x) {
      turnOffOnly(x);
      s = 'th' + x;
      f = document.getElementById("timelineForm");
      v = document.getElementById(s);
      if (v) v.value = '';
      f.submit();
      }

function turnOn(x) {
      turnOnOnly(x);
      s = 'th' + x;
      f = document.getElementById("timelineForm");
      v = document.getElementById(s);
      if (v) v.value = s;
      f.submit();
      }