title: Event notification if SWT Combo display list is visible
body: <p>I was checking for an event that indicates if the Combo display list is open, but did not see anything.</p>
  
  <p>I thought of a mouse down/up event hook, but I quickly realized that a user presses and releases the mouse to display the list. Also, one can use a keyboard.</p>
  
  <p>I saw <a href="https://stackoverflow.com/questions/14579847/how-to-check-if-the-swt-combo-is-currently-opened">this article</a>, which said to use the <code>getListVisible()</code> method, however that would either some sort of timer. A mouse up event is not quite accurate for implementing the check and a timer seems like major overkill for a simple task.</p>
  
  <pre><code>cboServers = new Combo(this.cmptLogHtsControl, SWT.BORDER | SWT.MULTI | SWT.V_SCROLL);
  cboServers.addMouseListener(new MouseAdapter()
  {
      @Override
      public void mouseDown(MouseEvent arg0)
      {
      }
      @Override
      public void mouseUp(MouseEvent arg0)
      {
      }
  });
  gridData = new GridData(GridData.FILL, GridData.FILL, true, true);
  gridData.widthHint = 300;
  cboServers.setLayoutData(gridData);
  this.cboServers.addSelectionListener(new SelectionAdapter()
  {
      @Override
      public void widgetSelected(SelectionEvent arg0)
      {
      }
  });
  </code></pre>
  
  <p>Am I missing something? Thoughts?</p>