window.onload = function() {
  document.onselectstart = function() {return false;} // ie
  document.onmousedown = function() {return false;} // mozilla
}

/* You can attach the events to any element. The following example
uses an element with the id 'page'. */

window.onload = function() {
  var element = document.getElementById('page');
  element.onselectstart = function () { return false; } // ie
  element.onmousedown = function () { return false; } // mozilla
}