How to insert shapes as PushButton displayable on the GraphicView?

I'm trying to integrate shapes (such as rectangles / squares / triangles) as PushButton, and when pressing on a button, want the selected shape to be selected.

But I want to make it displayable on my GraphicView with the selected color I made with my ColorWheel.

How can I do that?

Here a screen of my actual work below:

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