Signal-Android/app/src/main/res/drawable-night/progress_button_state.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"
          android:color="@color/core_ultramarine_light"/>
    <item android:state_focused="true"
          android:color="@color/core_ultramarine_light"/>
    <item android:state_enabled="false"
          android:color="@color/core_ultramarine_light"/>
    <item android:state_enabled="true"
          android:color="@color/core_ultramarine_light"/>
</selector>