title: rowspan of QGridLayout not working as expected
body: <p>Here is how to draw a button that spans 2 columns:</p>
  
  <pre><code>#include &lt;QtGui&gt;
  
  int main(int argv, char **args)
  {
      QApplication app(argv, args);
  
      QPushButton *foo = new QPushButton("foo");
      QPushButton *bar = new QPushButton("bar");
      QPushButton *baz = new QPushButton("baz");
  
      QGridLayout *layout = new QGridLayout();
      layout-&gt;addWidget(foo, 0, 0);
      layout-&gt;addWidget(bar, 0, 1);
      layout-&gt;addWidget(baz, 1, 0, 1, 2); // span 2 columns
  
      QWidget window;
      window.setLayout(layout);
      window.setWindowTitle("test");
      window.show();
  
      return app.exec();
  }
  </code></pre>
  
  <p>Running the code gives me:</p>
  
  <p><img src="https://i.stack.imgur.com/IpHrH.png" alt="enter image description here"></p>
  
  <p>If I change the layout in order to get a button, <code>baz</code>, that spans 2 rows I fail:</p>
  
  <pre><code>layout-&gt;addWidget(foo, 0, 0);
  layout-&gt;addWidget(bar, 1, 0);
  layout-&gt;addWidget(baz, 0, 1, 2, 1); // (try to) span 2 rows
  </code></pre>
  
  <p>Here is what I get:</p>
  
  <p><img src="https://i.stack.imgur.com/Fn9Um.png" alt="enter image description here"></p>