Make action key background more visually prominent

    <item android:state_single="true"

          android:drawable="@drawable/btn_keyboard_key_dark_normal_holo" />

    <!-- Action keys. -->

    <item android:state_active="true" android:state_pressed="true"

          android:drawable="@drawable/btn_keyboard_key_dark_pressed_holo" />

    <item android:state_active="true"

          android:drawable="@drawable/btn_keyboard_key_dark_active_holo" />

    <!-- Toggle keys. Use checkable/checked state. -->

    <item android:state_checkable="true" android:state_checked="true" android:state_pressed="true"

    <item android:state_checkable="true"

          android:drawable="@drawable/btn_keyboard_key_dark_normal_off_holo" />

    <!-- Normal keys -->

    <!-- Normal keys. -->

    <item android:state_pressed="true"

          android:drawable="@drawable/btn_keyboard_key_light_pressed_holo" />

            <!-- This should be aligned with Key.BACKGROUND_TYPE_* -->

            <enum name="normal" value="0" />

            <enum name="functional" value="1" />

            <enum name="action" value="2" />

        </attr>

        <!-- Whether this is a toggle key. -->

        <attr name="isSticky" format="boolean" />