Twitter: Smooth scrolling with TabLayout pin at top

Question

How does Twitter app implement their smooth scrolling with TabLayout that pins at the top?

Twitter app gif

I have tried the various combination of CoordinatorLayout, AppBarLayout, CollapsingToolbarLayout, and TabLayout/ViewPager. The closest I have is the following hierarchy.

<CoordinatorLayout>
    <AppbarLayout>
        <CollapsingToolbarLayout layout_scrollFlags="scroll|exitUntilCollapsed">
            <ImageView />
            <LinearLayout />
            <Toolbar layout_collapseMode="pin" />
        </CollapsingToolbarLayout >
    </AppbarLayout>
<LinearLayout layout_behavior="@string/appbar_scrolling_view_behavior">
    <TabLayout />
    <ViewPager />
</LinearLayout>

There are 2 problems I am trying to solve.

1 - Sometimes fling gesture gets bounced and applied to the opposite direction. 2 - I want one fling to scroll smoothly to the top and bottom. Currently, one fling to the top will once pause at TabLayout. Then I need to pull/fling up to reach the very top of the screen.

I am aware of this known bug with fling gesture in support library, but Twitter doesn't seem to have this bug. https://code.google.com/p/android/issues/detail?id=176589

[Edit] I have looked at these questions.

Android: pin TabLayout to top of Scrollview

Android Toolbar and User Image Animation Like Twitter