Should callbacks and event subscriptions be re-registered in OnPanelReload?

Unity Engine
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1

Hi!

I’m using UI Toolkit with PanelRenderer.OnPanelReload and I’m wondering what the recommended pattern is for registering callbacks and events.

For example, inside OnPanelReload I re-query my UI elements:

private void OnPanelReload()
{
    _button = root.Q<Button>("MyButton");

    _button.RegisterCallback<ClickEvent>(OnButtonClicked);
    _button.clicked += OnClicked;
}

Should I always unregister callbacks and events before registering them again, for example:

_button.UnregisterCallback<ClickEvent>(OnButtonClicked);
_button.RegisterCallback<ClickEvent>(OnButtonClicked);

_button.clicked -= OnClicked;
_button.clicked += OnClicked;

Or is it expected that OnPanelReload provides new VisualElement instances, making explicit unregistration unnecessary?

I know that RegisterCallback<T>() ignores duplicate registrations on the same VisualElement, while clicked += is a regular C# event and will accumulate subscriptions. However, I couldn’t find any official guidance on the recommended lifecycle for OnPanelReload.

Is there an official recommendation or best practice from Unity for handling callback registration in OnPanelReload?

Thanks!