WordPress/src/main/res/drawable/nux_primary_button_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_pressed="true">
        <shape xmlns:android="http://schemas.android.com/apk/res/android">
            <solid android:color="@color/blue_dark" />
            <corners android:radius="2dp" />
        </shape>
    </item>

    <item android:state_enabled="true">
        <shape xmlns:android="http://schemas.android.com/apk/res/android">
            <solid android:color="@color/blue_dark" />
            <corners android:radius="2dp" />
        </shape>
    </item>

    <item android:state_enabled="false">
        <shape xmlns:android="http://schemas.android.com/apk/res/android">
            <solid android:color="@color/blue_medium" />
            <corners android:radius="2dp" />
        </shape>
    </item>

    <item>
        <shape xmlns:android="http://schemas.android.com/apk/res/android">
            <solid android:color="@color/blue_dark" />
            <corners android:radius="2dp" />
        </shape>
    </item>
</selector>