title: How to get the columns of a jface Tree Viewer?
body: <p>Having a reference to a jface <code>TreeViewer</code>, how can you get a list of its columns, e.g. <code>TreeViewerColumn</code> objects? Something like:</p>
  
  <pre><code>TreeViewer treeViewer = (TreeViewer)viewer;
  TreeViewerColumn[] treeViewerColumns = treeViewer.getColumns();
  </code></pre>
  
  <p>Is it just me or there isn't an obvious way to do this?</p>
  
  <p>What I'm trying to do is to add editing support for items in Project Explorer. I have a reference to the Project Explorer's tree viewer, but I need to obtain its <code>TreeViewerColumn</code> and do:</p>
  
  <pre><code>column.setEditingSupport(...);
  </code></pre>