function showDialog(url) {
 closeDialog();

 var bg = document.createElement('div');
 bg.id = 'dialog_background';
 bg.className = 'dialog_bg';
 
 var div = document.createElement('div');
 div.id = 'dialog';
 div.className = 'dialog';
 div.innerHTML = '<p id="loading">Loading</p>';

 var a = document.createElement('a');
 a.id = 'dialog_close';
 a.className = 'dialog_close';
 a.innerHTML = 'Close';
 a.onclick = closeDialog; 

 document.body.appendChild(bg);
 document.body.appendChild(div);
 document.body.appendChild(a);

 new Ajax.Updater(div, url);
}

function closeDialog() {
 if ($('dialog') != null) {
  document.body.removeChild($('dialog'));
  document.body.removeChild($('dialog_background'));
  document.body.removeChild($('dialog_close'));
 }
}