and note the filetype name you use there and the filetype name used in the `filetype.XXX.conf` filename are case sensitive and must match exactly.
I'm not sure what you mean. I did this:
cp /usr/share/geany/filedefs/filetypes.c ~/.config/geany/filedefs/filetypes.Hare.confNo, as I said, look at and copy one of the _custom_ filetypes files, not a builtin filetype file, one that looks like filetype.XXX.conf.
Maybe start with filetypes.Swift.conf since it uses the C lexer. Also obviously whichever existing filetype file you copy you need to change the keywords lists unless your language has exactly the same ones.
Thanks, Lex. That worked.
-- John