I can confirm that the xenial-proposed version of gnome-software fixes this bug. I've just tested it with the 'atom-amd64.deb' package downloaded from atom.io and the dropbox package too.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1573408 Title: GNOME Software does not install third-party .deb packages To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-software/+bug/1573408/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
