Menu Question

Hi!
I need some help to make a menu that I’m planning to make!
I know that this is a bit complex to explain by words, but I’ll try (including also a picture about the menu).

So, I want to make a menu, with a bar that goes up and down depending wich button I click (probably I have top include coordinates x, y of the buttons, or not?!? ).
This bar will work as a Mask, and will give the “color” to the button.

I’m searching every forums including this one but I can’t find anything similar.
Can you guys help me please?

This picture shows the construction process and how it looks after is functional.
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Thanks in advance!
PS: Sorry, my bad english!