public void SetContent(IContentSource content)
 {
     source = content;
     treeView.Nodes.Clear();
     treeView.Nodes.AddRange(source.GetTree());
     // Assign icons
     foreach (var node in treeView.Nodes.All(Filter.EXCLUDE_CHILDREN))
     {
         node.ImageIndex         = 1;
         node.SelectedImageIndex = 1;
     }
 }