title: What does hot spot in Qt drag-and-drop mean?
body: <p>Qt has a method <code>QDrag::setHotSpot()</code> which</p>
  
  <blockquote>
    <p>sets the position of the hot spot relative to the top-left
    corner of the pixmap used to the point specified by hotspot.</p>
  </blockquote>
  
  <p>But what is hot spot and its function? How would you define it?</p>