instrument names not always properly centered in .40

[Francisco Vila]

Hello,
I've seen that in .40 instrument names are centered by default;
however, there is some problem because the longest name does not set
the width of the column where the names are centered in (see sample
and preview)

\version "2.11.40"
<<
\new Staff {\set Staff.instrumentName = "Violin I" c'1}
\new Staff {\set Staff.instrumentName = "Violin II" c'1}
\new Staff {\set Staff.instrumentName = "Viola" c'1}
\new Staff {\set Staff.instrumentName = "Tromba marina" c'1}
>>
\paper {
ragged-right=##t
%horizontal-shift = 5\cm
}

-- 
Francisco Vila. Badajoz (Spain)
http://www.paconet.org

instrumentName.preview.png
Description: PNG image