title: Qt Drag and drop between QTreeWidget
body: <p>In my QT application I have two QTreeWidget A and B.</p>
  
  <p>I want rewrite drag and drop function for this two behavior:</p>
  
  <ul>
  <li>From A to A move items with all childrens.</li>
  <li>From B to A copy items with all childrens.</li>
  </ul>
  
  <p>I have view that in dropEvent function I have event.source() for take source.</p>
  
  <p>But how change function with flag for movement or copy dinamically?</p>
  
  <p>There is an example?</p>
  
  <p>Thanks</p>