since

commit b8f21298
Author: Tomaž Vajngerl <tomaz.vajngerl@collabora.co.uk>
Date:   Mon Mar 2 20:57:32 2015 +0900

the color bar is always drawn under the icon and doesn't
get drawn to the right and fill all the empty space of
the tool item, e.g. in impress see the new toolbar color
selector

Change-Id: Ib70fec9c933b9d743e67475899938a5d9f405496