function getNewXMLHTTP()
{
  var xhr = false;
  if (window.XMLHttpRequest)
  {
    xhr = new XMLHttpRequest();
  }
  else if (window.ActiveXObject)
  {
    try
    {
      xhr = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch(e)
    {
      try 
      {
        xhr = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch(e)
      {
        xhr = false;
      }
    }
  }
  return xhr;
}


// Trigger an ajax request

function showMonth(year,month)
{
  try
  {
    xhr = getNewXMLHTTP();
    xhr.open("GET", "/ajax/calendar.php?y="+year+"&m="+month+"&r="+Math.random(), true);
    xhr.onreadystatechange = showMonthResponse;
    xhr.send(null);
  }
  catch(e)
  {
  }
}


// Callback handler when ajax request completes

function showMonthResponse()
{
  if (xhr.readyState == 4)
  {
    if (xhr.status == 200)
    {
      xhrresp = xhr.responseText;
      document.getElementById('left-calendar').innerHTML = xhrresp;
    }
  }
}