I am very confused about how RenderObjects are managed in Flutter. A RenderObject is created by its Element, But when exactly is the render object detached? What are the use cases for this?

here in below, i try to remove listener but its seem i also need to remove it at detach?

(context: I am trying to monopolize the focus event on this render object (its always return handled – this RenderObject is act like custom-text-laTex-table editor).

@override
  void attach(PipelineOwner owner) {
    super.attach(owner);
    FocusManager.instance.addEarlyKeyEventHandler(_documentController.keyboardHanlder);
  }

  @override
  void detach() {
    FocusManager.instance.removeEarlyKeyEventHandler(_documentController.keyboardHanlder);
    super.detach();
  }

  @override
  void dispose() {
    FocusManager.instance.removeEarlyKeyEventHandler(_documentController.keyboardHanlder);
    super.dispose();
  }

From the documentation, we know:

“Mark this render object as detached from its PipelineOwner.

Typically called only from the parent’s detach, and by the owner to
mark the root of a tree as detached.

Subclasses with children should override this method to detach all
their children after calling the inherited method, as in
super.detach().”

However, it’s still not clear to me why a render object would be detached but not disposed.

1. What are the specific scenarios where a render object is detached but not yet disposed?
2. So if its true, its mean we can create an element and create a render object, then attach it to another render object?

I appreciate any clarification or examples that can help me understand this better. Thank you.