title: NSForm disappearing from custom sheet
body: <p>I've made a custom sheet and it appears and disappears as necessary. However, the sheet includes an NSForm that disappears when automatic cell resizing is disabled. </p>
  
  <p>When "Auto recalculate cell size" is enabled, the form appears but the form's cells are not sized properly. </p>
  
  <p>Has anyone had this problem before? </p>