title: Show 2 Windows at Same time in Qt
body: <p>How can i show two windows at same time ?  Well i have a mainwindow ,then when i press a button i load a plugin which creates and return a qwidget, and set it as central widget <code>setCentralWidget()</code> ,but my app crashes .If i'm not wrong this anyway will show just one window at same time . </p>
  
  <p>Code from plugin :</p>
  
  <pre><code>QWidget* PlPlugin::initPltter() {
  
      plotter = new QWidget();
      plotter-&gt;resize(200,300);
      plotter-&gt;setWindowTitle("mypl");
      plotter-&gt;show();
  
      return plotter;
  }
  </code></pre>
  
  <p>In my app i'm doing :</p>
  
  <pre><code>setCentralWidget(plotter-&gt;initPlotter());
  </code></pre>