title: How to change font size of NSTableHeaderCell
body: <p>I am trying to change the font size of my NSTableView within my code to allow the user to change it to their liking. 
  I was successful by changing the font size of each NSTableCellView but failed to do so by the header cells.</p>
  
  <p>I was trying to do it like this</p>
  
  <pre><code>let headerCell = NSTableHeaderCell()
  let font = NSFont(name: "Arial", size: 22.0)
  headerCell.stringValue = "firstname"
  headerCell.font = font
  customerTable.tableColumns[0].headerCell = headerCell
  </code></pre>
  
  <p>The stringValue of the header cell will be set accordingly but the size does not change. How can I change the font size of my headers?</p>
  
  <p>Thanks</p>
  
  <p>Oliver</p>