sclass JForm is Swingable {
  new L parts;
  new FormLayout1 layout;
  JPanel panel;
  
  // true = close internal frame on submit
  // false = close frame on submit
  // null = close nothing on submit
  settable Bool willBeContainedInInternalFrame;
  
  *(O... parts) { this.parts = asList(parts); }
  
  quickVisual
    panel = jpanel(layout,
      showForm_arrange1(showForm_makeComponents(willBeContainedInInternalFrame,
        flattenToArray(parts))));
}