title: Problem naming NSTableColumn
body: <p>I'm trying to create a column with an empty string as the identifier but Cocoa seems to replace the empty string with the word "Field" every time I try to create the column. How do you go around this?</p>
  
  <pre><code>- (void)addColumnWithCheckboxToTable:(NSTableView *)table
  {
      // Add column with checkbox before all other columns
      // This column will have no title and should be as wide as the checkbox
      NSTableColumn *column = [[[NSTableColumn alloc] initWithIdentifier:@" "] autorelease];
  
      // The checkbox is to be initialised without a title
      NSButtonCell *checkbox = [[[NSButtonCell alloc] initTextCell:@" "] autorelease];
      [checkbox setEditable:YES];
      [checkbox setButtonType:NSSwitchButton];
      [checkbox setImagePosition:NSImageOnly];
      [checkbox setControlSize:NSSmallControlSize];
  
      // Add column with checkbox to table
      [column setDataCell:checkbox];
  
      // Add column to table
      [table addTableColumn:column];
  }
  </code></pre>