title: Query a TreeNodeCollection
body: <p>I have a treeview control on a windows form UI and it has a few nodes (with multiple child nodes).
  I want to query the nodes collection so as to, say, 
  1. select those whose name start with 'x'<br>
  2. select those which do not have any data in Node.Tag field.</p>
  
  <p>Can someone please suggest me a way to do this. Linq would make it easy and neat, but I found nothing much on Linq to query TreeNodeCollection.</p>
  
  <p>Thanks,</p>