sclass JForm is Swingable {
  new L parts;
  new FormLayout1 layout;
  JPanel panel;
  
  // called after form is submitted.
  // can set or change at any point after form is generated/shown
  settable IVF1<Component> frameCloser;
  
  *(O... parts) { this.parts = asList(parts); }
  
  cachedVisual
    panel = jpanel(layout,
      showForm_arrange1(showForm_makeComponents(
        c -> { frameCloser?.get(c); },
        flattenToArray(parts))));
        
  selfType closeInternalFrameOnSubmit() { frameCloser(l1 disposeInternalFrame); this; }
  selfType closeFrameOnSubmit() { frameCloser(l1 disposeFrame); this; }
  selfType closeNothingOnSubmit() { frameCloser(null); this; }
}