Your button is derived from
Control like everything you see on any Windows Form. Therefore you can use the
MouseEnter (not "over") and
MouseLeave events to accomplish your task.
On Enter, change image, create and display buttons, attach event handlers.
On Leave, change image back, destroy buttons.
If you need several of those special image buttons with buttons on them, make it a separate class with the mentioned event handlers overridden.
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