how 2 make LibreOffice the default app for RTF files?

[fred smith]

Can't figure out how to get F17 to use LibreOffice Writer when opening a
RTF file,... It seems to want to use  Calibre for that. :( The "Preferred
applications" item on the menu only offers a few programs, and LO isn't
one of 'em.

BTW, this is for the MATE desktop, though pretty much the same question
applies to XFCE or Gnome.

thanks!

-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us ----------------------------
                    Do you not know? Have you not heard? 
    The LORD is the everlasting God, the Creator of the ends of the earth. 
  He will not grow tired or weary, and his understanding no one can fathom.
----------------------------- Isaiah 40:28 (niv) -----------------------------