Font scaling seems to be broken

[Cameron Horsburgh]

Hi folks,

This could just be me, but I seem to be having a little trouble with
font scaling. Consider this score (it's not quite minimal because I
wanted to include a few grobs) : 

%%%%%%%%%%%%%%%%%%
\version "2.11.32"

\relative c''{
  
  \key aes \major
  aes2 c4 d| 
  \time 6/8
  \clef bass
  aes,8 bes c des?4 c8
}
\layout{
%  #(layout-set-staff-size 15)
%  #(layout-set-staff-size 26)
}
\paper{
  ragged-right = ##t
}
%%%%%%%%%%%%%%%%%%

This compiles and renders appropriately (I've attached PNGs of the
output.) However, if I uncomment the first line in the \layout block
the noteheads, time signature and other things seem to be too
small. If I uncomment the second they're too large. 

The same thing happens if I try the #(set-global-staff-size ??)
construct instead. 

Is this a bug or are my eyes getting old? 
-- 

=============================================
Cameron Horsburgh

=============================================

DefaultStaffSize.png
Description: PNG image

ReducedStaffSize.png
Description: PNG image

EnlargedStaffSize.png
Description: PNG image