title: Unable to set a tooltip with setData when using QListView with QStringListModel
body: <p>I'm using a QListView widget in my application with QStringListModel as the model. Here's the complete code:</p>
  
  <p><code>main.cpp</code></p>
  
  <pre><code>#include "mainwindow.h"
  #include &lt;QApplication&gt;
  
  int main(int argc, char *argv[])
  {
      QApplication a(argc, argv);
      MainWindow w;
      w.show();
  
      return a.exec();
  }
  </code></pre>
  
  <p><code>mainwindow.h</code></p>
  
  <pre><code>#ifndef MAINWINDOW_H
  #define MAINWINDOW_H
  
  #include &lt;QMainWindow&gt;
  class MainWindow : public QMainWindow
  {
      Q_OBJECT
  
  public:
      explicit MainWindow(QWidget *parent = 0);
  };
  
  #endif // MAINWINDOW_H
  </code></pre>
  
  <p><code>mainwindow.cpp</code></p>
  
  <pre><code>#include "mainwindow.h"
  #include &lt;QStringListModel&gt;
  #include &lt;QListView&gt;
  
  MainWindow::MainWindow(QWidget *parent)
      : QMainWindow(parent)
  {
      setFixedSize(400, 400);
  
      auto listView = new QListView;
      setCentralWidget(listView);
  
      auto model = new QStringListModel;
      listView-&gt;setModel(model);
  
      QStringList list;
      list &lt;&lt; "item 1" &lt;&lt; "item 2";
      model-&gt;setStringList(list);
      auto idx = model-&gt;index(0);
      model-&gt;setData(idx, "Some tooltip", Qt::ToolTipRole);
      model-&gt;setData(idx, "actually, item 11", Qt::DisplayRole);
  }
  </code></pre>
  
  <p>The result:</p>
  
  <p><a href="https://i.stack.imgur.com/LGwIG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LGwIG.png" alt="enter image description here"></a></p>
  
  <p>As can be seen, the second <code>setData</code> call succeeds and the item text is changed, but the tooltip simply doesn't work; I can hover my mouse as much as I want over the first entry, and nothing happens.</p>
  
  <p>What am I doing wrong?</p>