title: Binding properties of multiple tree views to the same ViewModel
body: <p>I am working on a MVVM implementation, where i'll spawn multiple views (side by side) each containing a tree control. </p>
  
  <p>each of the views will have a similar tree, with a copy of [almost] all the same items. </p>
  
  <p>I would like to synchronize the IsExpanded property on all the view/TreeView's.. </p>
  
  <p>meaning, if i collapse one node, i would like all of them to collapse (and some goes for column widths etc). </p>
  
  <p>One way to do this, would be to bind all views to the same viewmodel, and have a DependencyProperty on that ViewModel, and set up the binding as Two Way on each view. However, i need each view to be bound to a separate viewmodel so that it can display unique values. I just need to synchronize a few properties of the tree, such as IsExpanded and Width. </p>
  
  <p>What would be the best approach here?</p>