title: Why it uses d->eventFilters.prepend(obj) not append(obj) in function(QObject::installEventFilter)
body: <p>Why it uses <code>d-&gt;eventFilters.prepend(obj)</code> not append(obj) in function(<code>QObject::installEventFilter</code>),i want to know why design it in such way.I just curious about it.</p>
  
  <pre><code>    void QObject::installEventFilter(QObject *obj)
  {
      Q_D(QObject);
      if (!obj)
          return;
      if (d-&gt;threadData != obj-&gt;d_func()-&gt;threadData) {
          qWarning("QObject::installEventFilter(): Cannot filter events for objects in a different thread.");
          return;
      }
  
      // clean up unused items in the list
      d-&gt;eventFilters.removeAll((QObject*)0);
      d-&gt;eventFilters.removeAll(obj);
      d-&gt;eventFilters.prepend(obj);
  }
  </code></pre>