Q: How to restore the original icons for Mozilla Thunderbird?

1. Read General Notes

2. wget -c https://frankandjacq.com/ubuntuguide/mozilla-thunderbird.xpm
   chmod 644 mozilla-thunderbird.xpm
   sudo dpkg-divert --rename /usr/share/pixmaps/mozilla-thunderbird.xpm
   sudo dpkg-divert --rename /usr/share/pixmaps/mozilla-thunderbird-menu.xpm
   sudo dpkg-divert --rename /usr/share/pixmaps/mozilla-thunderbird-pm-menu.xpm
   sudo dpkg-divert --rename /usr/lib/mozilla-thunderbird/chrome/icons/default/mozilla-thunderbird.xpm
   sudo dpkg-divert --rename /usr/lib/mozilla-thunderbird/chrome/icons/default/messengerWindow16.xpm
   sudo dpkg-divert --rename /usr/lib/mozilla-thunderbird/chrome/icons/default/messengerWindow.xpm
   sudo dpkg-divert --rename /usr/lib/mozilla-thunderbird/chrome/icons/default/default.xpm
   sudo cp mozilla-thunderbird.xpm /usr/share/pixmaps/mozilla-thunderbird.xpm
   sudo cp mozilla-thunderbird.xpm /usr/share/pixmaps/mozilla-thunderbird-menu.xpm
   sudo cp mozilla-thunderbird.xpm /usr/share/pixmaps/mozilla-thunderbird-pm-menu.xpm
   sudo cp mozilla-thunderbird.xpm /usr/lib/mozilla-thunderbird/chrome/icons/default/mozilla-thunderbird.xpm
   sudo cp mozilla-thunderbird.xpm /usr/lib/mozilla-thunderbird/chrome/icons/default/messengerWindow16.xpm
   sudo cp mozilla-thunderbird.xpm /usr/lib/mozilla-thunderbird/chrome/icons/default/messengerWindow.xpm
   sudo cp mozilla-thunderbird.xpm /usr/lib/mozilla-thunderbird/chrome/icons/default/default.xpm

3. Read How to restart GNOME without rebooting computer?