title: NSScrollView doesn't scroll when adding NSSegmentedControl
body: <p>I have an empty NSScrollView created with Interface Builder.</p>
  
  <p>And in my code I add, upon a user click, a NSSegmentedControl. For all the next clicks, I add a segment to it.</p>
  
  <p>My problem is that, once I reach the visual limit of NSScrollView, it doesn't start to scroll and all the post-limit segments are never shown.</p>
  
  <p>This is the NSScrollView from Interface Builder : </p>
  
  <p><img src="https://i.stack.imgur.com/6L0s6.png" alt="enter image description here"></p>
  
  <p>And here is the method :</p>
  
  <pre><code>- (IBAction)addSegment:(id)sender
  {
      if (segCtrlColumns == nil) {
          segCtrlColumns = [[NSSegmentedControl alloc] initWithFrame:[self.viewColumns frame]]; //self.viewColumns is the NSScrollView from IBOutlet
          [segCtrlColumns setSegmentCount:1];
          [segCtrlColumns setLabel:@"Test" forSegment:0];
          [segCtrlColumns setTarget:self];
      } else {
          double increaseSegments = [segCtrlColumns segmentCount]+1;
          [segCtrlColumns setSegmentCount:increaseSegments];
          [segCtrlColumns setLabel:@"Test" forSegment:increaseSegments-1];
      }
      [self.viewColumns setDocumentView:segCtrlColumns];
  }
  </code></pre>
  
  <p>And here is the problem :</p>
  
  <p><img src="https://i.stack.imgur.com/OjZMm.png" alt="enter image description here"></p>
  
  <p>(Well it is more likely "nothing to scroll" than "not scrollable")</p>