navigation_button_background.xml

Enable keyboard shortcuts

<?xml version="1.0" encoding="utf-8"?>

<!-- This Source Code Form is subject to the terms of the Mozilla Public

   - License, v. 2.0. If a copy of the MPL was not distributed with this

   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item>

        <selector>

            <item android:drawable="@drawable/circle_button_background" />

        </selector>

    </item>

    <item>

        <ripple android:color="@android:color/transparent">

            <item android:id="@android:id/mask">

                <shape android:shape="oval">

                    <solid android:color="@android:color/black" />

                </shape>

            </item>

        </ripple>

    </item>

</layer-list>