session-android/res/drawable/conversation_item_background_animated.xml

<?xml version="1.0" encoding="UTF-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" android:exitFadeDuration="1000">
    <item android:drawable="@color/textsecure_primary_alpha33" android:state_selected="true" />
    <item android:drawable="@color/signal_primary_alpha_focus" android:state_focused="true" />
</selector>