[texworks] Changing texworks-config.txt?

[Duncan Murdoch]

I have some old notes that say to change the file types listed in the 
File Open dialog, I should edit the texworks-config.txt file in the 
configuration directory.  I'm on a Mac, and see this file in 
~/Library/TeXworks/configuration, but changes there appear to have no 
effect when I open TeXworks again.  I still see the old file types, i.e.

   TeX documents (*.Rnw *.tex)

(which I think are customized from the defaults), when what I want to see is

   TeX documents (*.Rnw *.Rmd *.tex)

Here's what I now have in 
~/Library/TeXworks/configuration/texworks-config.txt:

   # To override the built-in list of file types in the File/Open dialog,
   # uncomment and customize these entries:
   #
   file-open-filter:	TeX documents (*.Rnw *.Rmd *.tex)
   ... more filters, some commented ...

Do I need to do something to get TeXworks to read that file again?  Or 
am I looking in the wrong place?

Duncan Murdoch