k-9/res/layout/message_view_bottom_buttons.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout
        android:id="@+id/bottom_buttons"
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingRight="6dip"
        android:background="@android:color/transparent"
        android:gravity="center_vertical">
        <Button
            android:id="@+id/previous"
            android:text="@string/message_view_prev_action"
            android:contentDescription="@string/previous_action"
            android:textSize="35dip"
            android:padding="0dip"
            android:layout_height="wrap_content"
            android:layout_width="0dip"
            android:layout_weight="1" />

        <ImageButton
            android:id="@+id/delete"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_button_delete"
            android:textSize="0dip"
            android:layout_width="0dip"
            android:layout_weight="1" />
       <Button
            android:id="@+id/next"
            android:text="@string/message_view_next_action"
            android:contentDescription="@string/next_action"
            android:textSize="35dip"
            android:padding="0dip"
            android:layout_height="wrap_content"
            android:layout_width="0dip"
            android:layout_weight="1" />
    </LinearLayout>
</merge>