Change fast scroll alphabet bubble

Question

I am trying to change a bubble containing a letter in a scroll bar.

What is its official name BTW?

I'm not talking about fastScrollThumbDrawable or fastScrollTrackDrawable on the right side. See image below.

• How to change the color of this bubble?

This answer uses colorAccent . But I do not want to touch on the topic.

2. How to reposition this bubble?

Huby's answer on How to handle a fast scroller on Lollipop 5.1 gives a partial response to changing the location of the bubble