RetroMusicPlayer/app/src/main/res/drawable/widget_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:drawable="@color/ripple_material_dark" android:state_activated="true" android:state_pressed="true" />
    <item android:drawable="@color/ripple_material_dark" android:state_activated="true" />
    <item android:drawable="@color/ripple_material_dark" android:state_pressed="true" />
    <item android:drawable="@android:color/transparent" />

</selector>