title: View-based NSOutlineView header cell font issues
body: <p>I'm currently trying to use a new view-based NSOutlineView in my Cocoa app. As I'm not using bindings, so I implemented all required delegate and datasource methods in my controller. </p>
  
  <p>In interface builder I've added a NSOutlineView with a highlighting set to <em>SourceList</em> and Content Mode set to <em>View Based</em>. Thus, there were two default table cell views provided (one Header cell with <em>HeaderCell</em> set as identifier and one data cell with <em>DataCell</em> set as identifier)</p>
  
  <p>This is what it looks like in interface builder, header cell views correctly show a grey-blue <em>textField</em> while data cell views have a image view and a <em>textField</em> with correct color and font settings
  <img src="https://i.stack.imgur.com/4yZzX.png" alt=""></p>
  
  <p>To provide the views, I use the following code, to return a DataCell-view or a HeaderCell-view and set the textField of the cell accordingly, based on the corresponding identifier set in interface builder. </p>
  
  <pre><code>- (NSView *)outlineView:(NSOutlineView *)outlineView 
       viewForTableColumn:(NSTableColumn *)tableColumn 
                     item:(id)item {
  
  
      NSTableCellView *result = nil;
  
      if ([item isKindOfClass:[NSMutableDictionary class]]) {
          result = [outlineView makeViewWithIdentifier:@"HeaderCell" owner:self];
  
          id parentObject = [outlineView parentForItem:item] ? [outlineView parentForItem:item] : groupedRoster;
          [[result textField] setStringValue:[[parentObject allKeys] objectAtIndex:0]];
  
  
      } else {
          result = [outlineView makeViewWithIdentifier:@"DataCell" owner:self];
  
          [item nickname] ? [[result textField] setStringValue:[item nickname]] : [[result textField] setStringValue:[[item jid] bare]];
      }
      return result;
  }
  </code></pre>
  
  <p>Running everything it looks like the following.
  <img src="https://i.stack.imgur.com/ZAWaY.png" alt=""></p>
  
  <p>Could anybody provide me with hints, to why the header cell is neither bold, nor correctly colored, when selected?</p>