Signal-Android/res/drawable/emoji_category_recent_light.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
          android:enterFadeDuration="200"
          android:exitFadeDuration="300">
	<item android:state_selected="true" android:drawable="@drawable/ic_emoji_recents_activated_light" />
	<item android:drawable="@drawable/ic_emoji_recents_normal_light" />
</selector>