title: QT QCustomPlot parent
body: <p>I have a <code>QCustomPlot</code> widget in my ui as follows:</p>
  
  <pre><code>ui-&gt;plot_widget
  </code></pre>
  
  <p>also I have another <code>QCustomPlot</code> object in my cpp file as follows:</p>
  
  <pre><code>QCustomPlot *plot=new QCustomPlot();
  </code></pre>
  
  <p>I want to add <code>plot</code> data into <code>ui-&gt;plot_widget</code> data.
  If I use <code>ui-&gt;plot_widget=plot</code> the widget parent of <code>ui-&gt;plot_widget</code> will be destroyed and my ui does not update <code>ui-&gt;plot_widget</code>.</p>
  
  <p>How can I add <code>plot</code> data into <code>ui-&gt;plot_widget</code> data?</p>