Comment 33 for bug 1765726

Here is a more or less complete list of optional dependencies (package names may vary since it is from the Arch Linux PKGBUILD):

optdepends=('gnome-web-photo: web screenshot support'
  'perl-image-exiftool: read and write EXIF data'
  'nautilus-sendto: send screenshots via mail'
  'perl-goo-canvas: editing screenshots'
  'perl-gtk2-appindicator: AppIndicators support'
  'perl-path-class: Imgur and Dropbox upload support'
  'perl-lwp-protocol-https: Imgur and Dropbox upload support'
  'perl-net-oauth: Imgur and Dropbox upload support'
  'bc: 3D Rotate and 3D Reflection plugins support')

Maybe some Ubuntu user could check which of them are missing in 18.04?