title: How to remove Qt icon from QMdiSubWindow
body: <p>Trying to remove the Qt Icon from a QMdiSubWindow with little success. Below is a picture showing the icon in the top left corner.</p>
  
  <p><img src="https://i.stack.imgur.com/Viluw.jpg" alt="enter image description here"></p>
  
  <p>Here is some code, which seems like it should set the Icon to empty, but does not.</p>
  
  <pre><code>QMdiSubWindow* sub = new QMdiSubWindow;
  
  sub-&gt;setAttribute( Qt::WA_DeleteOnClose );
  sub-&gt;setWidget( myWidget );
  sub-&gt;setWindowIcon( QIcon() );
  //tried this too
  //sub-&gt;setWindowIcon( QIcon("") );
  
  mdiArea-&gt;addSubWindow( traceSub );
  </code></pre>
  
  <p>Thanks!</p>