I've put a diff that fixes this bug at
http://www.tww.cx/downloads/fontcase.diff
I'd love to say that there must be an easier way but instead I'd like to say that the person that defined the C++ string class without case-changing functions should themselves be strung up!
The method used needs to be checked by someone who actually knows C++ to see if it will handle non-ASCII font names. I don't have any such fonts to test it with and I'm not sure enough about how C++'s toupper function works on unicode to even guess whether it will work or not.
The diff file also adds some comments to toolbox.cpp. Thanks to Gail for pointing me in the direction of that file, BTW, it would have taken me even longer to come up with a fix without her quick reply to my query.
Finally, the diff file has some changes to a pair of makefiles which are a mystery to me; I never touched them, Gov'nor!
Thomas