title: Trying to add a menu to a TableViewer's header row (titles row)
body: <p>I am trying to add an action to a menu to the header (titles) of a TableViewer.</p>
  
  <p>This is the code that I am using now:</p>
  
  <pre><code>    viewer = new TableViewer(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL 
                                           | SWT.FULL_SELECTION | SWT.BORDER);
      //...
  
      MenuManager manager = new MenuManager();
      viewer.getControl().setMenu(manager.createContextMenu(viewer.getControl()));
  
  
      manager.add(new Action("MENU ITEM TEXT") {
          @Override
          public void run() {
              // get the current selection of the tableviewer
              IStructuredSelection selection = (IStructuredSelection) viewer.getSelection();
              // do something
              if (selection.getFirstElement() instanceof MyObject)
                  return;
              System.out.println("OK: "+selection.getFirstElement().getClass().getName());
          }
      });
  </code></pre>
  
  <p>And this is how it looks:</p>
  
  <p><img src="https://i.stack.imgur.com/PWGLC.png" alt="enter image description here"></p>
  
  <p><strong>The problem is that the menu gets added to the entire TableViewer, not only to the header row.</strong>
  Because for the other rows I will need to use a different menu.
  I have tryied to find a way of adding the action only to the top row (the titles row), but with no success so far.<br/><br/>
  So how can I add the menu only for the header?</p>