protected boolean doFilter(Viewer viewer, Object element) {
    	IContentProvider cProvider = ((TreeViewer)viewer).getContentProvider();

    	// Check if element is visible
    	boolean ret = filterElement(element);
    	
    	if (!ret)
    	{
    		if (cProvider instanceof ITreeContentProvider)
	    	{
    			ITreeContentProvider treeContentProvider = (ITreeContentProvider) cProvider;
    			// If not visible, recursively check if a child element is visible, in which case the element must also be visible
    	    	if (treeContentProvider.hasChildren(element))
	    		{
	    			Object[] children = treeContentProvider.getChildren(element);
	    			for (Object child: children)
	    			{
	    				ret = doFilter(viewer, child);
	    				if (ret)
	    				{
	    					break;
	    				}
	    			}
	    		}
	    		
	        	// If still not visible and element is leaf, check if one of the siblings is visible 
    	    	if (!ret && !treeContentProvider.hasChildren(element))
	        	{
	        		Object parent = treeContentProvider.getParent(element);
	        		Object[] siblings = treeContentProvider.getChildren(parent);
	        		for (Object sibling: siblings)
	    			{
	        			if (sibling.equals(element))
	        			{
	        				continue;
	        			}
	        			
	        			// Check if sibling passes filter
	        			ret = filterElement(sibling);
	        			
	        			if (ret)
	        			{
	        				break;
	        			}
	    			}
	    			
	    			
	        	}

	    	}
	    	
	    	
    	}
    	
    	return ret;
    }
    
    private boolean filterElement(Object element) {
    	// do some filtering here
		return true;
	}

public boolean select(Viewer viewer, Object parentElement,
				Object element) {
}