Monday as first day in Gnome-Shell (instead of Sunday)

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http://askubuntu.com – I've been dealing with different regional settings (US, Canada and other locations in English, as well as other countries and languages), but I cannot get Gnome-shell Calendar to begin with Monday, instead of Sunday (see image). I have even modified the "en_US" file in /usr/share/i18n/locales/ (line: first workday: 1). All without success. My question is if it is hard-coded in Gnome-shell or it can be changed. Answers to this previous question doesn't apply to Gnome-shell. (HowTos)