If you need to get the Y position of a vertically scrolling container, create a text box. Then on the container scroll trigger, set a variable that evaluates the numerical callback value from the event (Y position). Then add a callback that changes the text property of the text box by reading from the variable.

Ferry App

An example of a sticky scrolling sidebar (website)

Basic layout for a material design shopping app with easy to access categories, and "shopping cards."