lawnchair/res/color/overview_button.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:alpha="1"
        android:color="?android:attr/textColorPrimary"
        android:state_enabled="true" />
    <item
        android:alpha="?android:disabledAlpha"
        android:color="?android:attr/textColorPrimary"
        android:state_enabled="false" />
</selector>