While the need to listen to scroll events of arbitrary views in Android has always existed, no such mechanisms were provided by Google until Android API level 23. That is when View.OnScrollChangeListener made its appearance. Until then, some views (e.g ListView) had custom mechanisms to listen to scroll events, but there was no common way. We, at Bugsee, have faced this problem while working on automatic concealment of protected web page elements (see Bugsee Privacy). We had to know when elements change their position, and no such mechanism exists for WebView for earlier Android versions.