title: Datagrid not updated when item property for filter changes
body: <p>I have a simple form with datagrid and a button. Items in the datagrid are bound to <code>ObservableCollection</code> of <code>customers</code>. The <code>customer</code> implements <code>INotifyPropertyChanged</code> interface. Each customer has a <code>deleted</code> property (type bool). I set a filter for the customers default view to filter out deleted customers based on the <code>deleted</code> property. So far it works.</p>
  
  <p>Then I add an event for the button that marks selected customer as deleted. The problem is the grid is not updated after setting <code>selected_customer.deleted = true</code>. The deleted customer is still visible. The column bound to <code>deleted</code> property updates correctly. To remove the customer from the grid, I have to manually call <code>Refresh()</code> method of the customers default view.</p>
  
  <p>Why is not the datagrid updated automaticaly when I use <code>ObservableCollection</code> and the customer implements <code>INotifyPropertyChanged</code> interface? How to make it update automatically?</p>