k-9/res/layout/actionbar_top_custom.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:clickable="true"
    android:focusable="true" >

    <ImageButton
        android:id="@+id/actionbar_refresh_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@null"
        android:layout_alignParentRight="true"
        android:src="@drawable/ic_menu_refresh" />

</RelativeLayout>