Merge pull request #6296 from thundernest/view_pager_margin

import android.view.ViewGroup

import androidx.fragment.app.Fragment

import androidx.recyclerview.widget.DiffUtil

import androidx.recyclerview.widget.DividerItemDecoration

import androidx.viewpager2.adapter.FragmentStateAdapter

import androidx.viewpager2.widget.MarginPageTransformer

import androidx.viewpager2.widget.ViewPager2

import com.fsck.k9.controller.MessageReference

import com.fsck.k9.ui.R

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {

        val view = inflater.inflate(R.layout.message_view_container, container, false)

        val resources = inflater.context.resources

        val pageMargin = resources.getDimension(R.dimen.message_view_pager_page_margin).toInt()

        viewPager = view.findViewById(R.id.message_viewpager)

        viewPager.isUserInputEnabled = true

        viewPager.offscreenPageLimit = ViewPager2.OFFSCREEN_PAGE_LIMIT_DEFAULT

        viewPager.addItemDecoration(DividerItemDecoration(context, DividerItemDecoration.HORIZONTAL))

        viewPager.setPageTransformer(MarginPageTransformer(pageMargin))

        viewPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {

            // The message list is updated each time the active message is changed. To avoid message list updates

            // during the animation, we only set the active message after the animation has finished.

    <dimen name="input_label_vertical_spacing">8dp</dimen>

    <dimen name="input_label_horizontal_spacing">4dp</dimen>

    <dimen name="account_setup_margin_between_items_incoming_and_outgoing">12dp</dimen>

    <dimen name="message_view_pager_page_margin">16dp</dimen>

</resources>