docs: function selectable ( elem, bool ){
  	if ( !elem ) return; // maybe element was removed ?
  	elem = elem.ownerDocument ? elem.ownerDocument : elem;
  	elem.unselectable = bool ? "off" : "on"; // IE
  	if ( elem.style ) elem.style.MozUserSelect = bool ? "" : "none"; // FF
  	$.event[ bool ? "remove" : "add" ]( elem, "selectstart mousedown", dontStart ); // IE/Opera
  	}