session-android/res/drawable/emoji_toggle_background.xml

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

<selector xmlns:android="http://schemas.android.com/apk/res/android">

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

    <item android:state_focused="true"
          android:drawable="@android:color/transparent" />

    <item android:drawable="@android:color/transparent" />

</selector>