What is the event for

I have ToolStrip control with the property AllowItemReorder is enabled which allows the items to be reordered when the ALT key is pressed, i want to save the ToolStrip when this happens but i don't know which event should i code!

Edit:
I did some tests and found these events are fires when reorder buttons ItemAdded, and ItemRemoved, maybe there are others.

Which one is suitable to use for saving the ToolStrip?