We are going to use a custom drawable for the button below. The custom drawable is defined by the file button_custom.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <Button
        android:id="@+id/saveButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="@string/save_label" 
                    android:background="@drawable/holo_blue_light"
/>

</RelativeLayout>

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

    <item
        android:drawable="@android:color/darker_gray"
        android:state_pressed="true"/>
    <item
        android:drawable="@android:color/holo_blue_light"
        android:state_focused="true"/>

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

</selector>