title: View-based “Source List” NSOutlineView not display icons and titles of the items
body: <p>After changing NSOutlineView cell-based to view-based, it's not display the icons and titles of file-system tree. Here my code:</p>
  
  <pre><code>- (void)outlineView:(NSOutlineView *)outlineView willDisplayCell:(id)cell forTableColumn:(NSTableColumn *)tableColumn item:(id)item {
      if ([[tableColumn identifier] isEqualToString:@"name"])
          return [(ImageAndTextCell *)cell setTextFieldImage:[item icon]];
  }
  
  - (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)item {
      return [((ConstructorFSEntity *)item) title];
  }
  
  - (NSView *)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item {
      if ([item isKindOfClass:[FSEntity class]]) {
          return [outlineView makeViewWithIdentifier:@"HeaderCell" owner:self];
      } else {
          return [outlineView makeViewWithIdentifier:@"DataCell" owner:self];
      }
  }
  </code></pre>
  
  <p>And I've one more question. How to put the enumerated items (array of file system's item) to the cell "DataCell", and "HeaderCell" declare as parent folder (group) and assign it a title (for example, @ "Root Folder") and the path of the class. Because, now previous view-based method,  displayed enumerated item only in "HeaderCell" or "DataCell" and when I trying assign to "HeaderCell" a some value,  the app crashing. Can you help me with this?</p>