/**
  * 设置窗口私有属性
  *
  * @param name Name of the attribute to set
  * @param value Value of the attribute to set
  */
 public void setAttribute(String name, Object value) {
   if (name == null) {
     throw new NullPointerException("don't set a NULL named attribute");
   }
   if (value == null) {
     removeAttribute(name);
     return;
   }
   synchronized (mutex) {
     window.set(name, value);
     if (deleteAttributes != null) {
       deleteAttributes.remove(name);
     }
   }
 }