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.

This is the redesign of GoodReads app for Android. Hope you guys love it, and I would love to know your views about it!

An example of a sticky scrolling sidebar (website)

This prototype show how to re-create the intro animation of the Twitter iOS app where the bird flings out and the feed flings in. See how it was re-created step-by-step in this webinar video: http://docs.proto.io/videos/re-creating-bespoke-interactive-animations-with-proto-io-2/ Assets also available to use.