MouseOver UI Tutorial
This is an easy way to do nice, interactive UI with almost no code.
Just attach an EventTrigger to your button and tell it to make things appear and disappear. If you don't like making functions to do that, you can actually drag the visuals into the event target spot and tell it to enable or disable them directly!
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Some of the keywords you might hope would find this tutorial:
EventTrigger, PointerEnter, MouseOver, MouseEnter...