title: flex : add checkbox to datagrid control
body: <p><br>
  i have a datagrid in my flex application, i am binding datagrid with arrayCollection, 
  now i want to add checkbox control to datagrid column and i dont want to bind chekcbox to arraycollection values. 
  i want something like  <a href="http://groups.google.com/group/flex_india/browse_thread/thread/2553d697c6b5fdec" rel="nofollow">this</a>
  without binding checkbox column field with arryayCollection.</p>