How do I use SelectionImageObject?

Hello developers,

As of recently, I have been adding gamepad support to my game. Though, I feel that the style of the current SelectionImageObject doesn’t fit the game. I decided to create my own, but I do not know how to size or position the GuiObject it points to, and I have looked all over with no answer. I followed this tutorial, but it didn’t really work in the end.