[Rd] One possible cause for incorrect symbols in X11() output

[Prof Brian Ripley]

There have been spasmodic reports of symbols such as pi and infinity 
in plotmath being reproduced incorrectly on the X11 device on some 
Linux systems (at least Ubuntu 10 and Fedora 12/13), and we've managed 
to track down one cause whilst investigating PR#14355.

Some systems have Wine and hence the Wine symbol font installed. 
'fontconfig', which is used by cairographics in X11(type='cairo') and 
many other applications, prefers the Wine symbol font to the standard 
Type 1 URW font, and seems to misinterpret its encoding.

You may well have Wine installed without realizing it (as I did) -- it 
is increasingly common as a dependency of other software. The best 
test is to run

% fc-match symbol
s050000l.pfb: "Standard Symbols L" "Regular"

This is the result on a system without Wine: if you see

% fc-match symbol
symbol.ttf: "Symbol" "Regular"

you at least potentially have the problem.  A good test is to look at 
?points and run the function TestChars() defined there as

TestChars(font=5)

If you do have the problem, a workaround is to add the following lines 
to ~/.fonts.conf or /etc/fonts/local.conf (which you may need to 
create):

<match target="pattern">
   <test name="family"><string>Symbol</string></test>
   <edit name="family" mode="prepend" binding="same">
     <string>Standard Symbols L</string>
   </edit>
</match>

and repeat the fc-match test to check that it worked.

(This workaround was culled from
https://bugs.launchpad.net/ubuntu/+source/fontconfig/+bug/551977
)

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595