Auto-hiding Toolbar On Scroll, When There Are Several Other Layers Of Views In-between

I would like my activity's Toolbar to smoothly scroll out as a given scrollview grows, and then smoothly scroll back in if the user scrolls down. I.e. the basic scroll|enterAlways

Solution 1:

It turns out I need to use NestedScrollView, since, unlike its name suggested to me, it is not just for nesting ScrollViews into other ScrollViews, but also for nesting a ScrollView inside other containers:

NestedScrollView is just like ScrollView, but it supports acting as both a nested scrolling parent and child on both new and old versions of Android.