old_contents: var properties = arguments[0];
  
  $.button.backgroundImage = properties.properties.backgroundImage || WPATH('images/button/back.png');
  $.button.title = properties.properties.title || L('back');
  $.button.addEventListener('click', function(e) {
      properties.pageflow.back();
  });
  
new_contents: var properties = arguments[0];
  
  $.button.backgroundImage = properties.properties.backgroundImage;
  $.button.title = properties.properties.title || L('back');
  $.button.addEventListener('click', function(e) {
      properties.pageflow.back();
  });
  
subject: Remove default back button