title: Lazy and Deferred TreeViewer questions
body: <p>I have actually two questions but they are kind of related so here they go as one...</p>
  
  <p>How to ensure garbage collection of tree nodes that are not currently displayed using <code>TreeViewer</code>(<code>SWT.VIRTUAL</code>) and <code>ILazeTreeContentProvider</code>?
  If a node has 5000 children, once they are displayed by the viewer they are never let go,
  hence Out of Memory Error if your tree has great number of nodes and leafs and not big enough heap size.
  Is there some kind of a best practice how to avoid memory leakages, caused by never closed view holding a treeviewer with great amounts of data (hundreds of thousands objects or even millions)?
  Perhaps maybe there is some callback interface which allow greater flexibility with viewer/content provider elements?</p>
  
  <p>Is it possible to combine deffered (<code>DeferredTreeContentManager</code>) AND lazy (<code>ILazyTreeContentProvider</code>) loading for a single <code>TreeViewer</code>(<code>SWT.VIRTUAL</code>)?
  As much as I understand by looking at examples and APIs, it is only possible to use either one at a given time but not both in conjunction, e.g. ,
  fetch ONLY the visible children for a given node AND fetch them in a separate thread using Job API. What bothers me is that Deferred approach
  loads ALL children. Although in a different thread, you It still load all elements
  even though only a minimal subset are displayed at once.</p>
  
  <p>I can provide code examples to my questions if required...</p>
  
  <p>I am currently struggling with those myself so If I manage to come up with something in the meantime I will gladly share it here.</p>
  
  <p>Thanks!</p>
  
  <p>Regards,
  Svilen</p>