function updateElementWithUrl( element, url ) {
  var xhr = null;
  
  if(window.XMLHttpRequest) // Firefox and others
     xhr = new XMLHttpRequest(); 
  else if(window.ActiveXObject){ // Internet Explorer 
     try {
        xhr = new ActiveXObject("Msxml2.XMLHTTP");
      } catch (e) {
        xhr = new ActiveXObject("Microsoft.XMLHTTP");
      }
  }
  else { // XMLHttpRequest isn't supported by navigator
     alert("Your browser is unable to process XMLHTTPRequest objects. Please update."); 
     return;
  } 
  xhr.open("GET", url, true );
  
  xhr.onreadystatechange = function () {
    if ( xhr.readyState == 4 && xhr.status == 200 ) {
      if ( xhr.responseText != '' ) { 
        element.innerHTML = xhr.responseText;
      }
    }
  };
  
  xhr.send( null );
}

function updateElementWithUrlIfNull( element, url ) {
  var xhr = null;
  
  if(window.XMLHttpRequest) // Firefox and others
     xhr = new XMLHttpRequest(); 
  else if(window.ActiveXObject){ // Internet Explorer 
     try {
        xhr = new ActiveXObject("Msxml2.XMLHTTP");
      } catch (e) {
        xhr = new ActiveXObject("Microsoft.XMLHTTP");
      }
  }
  else { // XMLHttpRequest isn't supported by navigator
     alert("Your browser is unable to process XMLHTTPRequest objects. Please update."); 
     return;
  } 
  xhr.open("GET", url, true );
  
  xhr.onreadystatechange = function () {
    if ( xhr.readyState == 4 && xhr.status == 200 ) {
      if ( xhr.responseText != '' ) { 
        element.innerHTML = xhr.responseText;
      } else {
        element.innerHTML = '';
      }
    }
  };
  
  xhr.send( null );
}

function revertCheckboxes( targetForm, targetObject ) {
  var amount = targetForm.elements[ targetObject ].length;
  for ( i = 0; i < amount; i++ ) {
    if ( targetForm.elements[ targetObject ][i].checked ) { 
      targetForm.elements[ targetObject ][i].checked = false;
    } else { 
      targetForm.elements[ targetObject ][i].checked = true;
    }
  }
}

function toggleShow( targetElement ) {
  if ( targetElement.style.display == '' ) {
    targetElement.style.display = 'none';
  } else {
    targetElement.style.display = '';
  }
}