// makeNewComponent: func(Component) -> Component
//                   or Component
static Component awtReplaceComponent(Component c, O makeNewComponent) {
  ret (Component) swing(func { 
    Container parent = c.getParent();
    assertNotNull("woot", parent);
    Component[] l = parent.getComponents();
    LayoutManager layout = parent.getLayout();
    if (!(layout instanceof BorderLayout || layout instanceof ViewportLayout))
      warn("awtReplaceComponent only tested for BorderLayout/ViewportLayout. Have: " + layout);
    int idx = indexOf(l, c);
    if (idx < 0) fail("component not found in parent");
    //print("idx: " + idx);
    //print("Parent: " + parent);
    O constraints = callOpt(layout, "getConstraints", c);
    //print("Constraints: " + constraints);
    
    // remove
    parent.remove(c);
  
    // add new component  
    Component newComponent = (Component) (makeNewComponent instanceof Component ? makeNewComponent :  callF(makeNewComponent, c));
    parent.add(newComponent, constraints, idx);
    validateFrame(parent);
    ret newComponent;
  });
}