libgdm-dev 3.26.2.1-0ubuntu1 (s390x binary) in ubuntu bionic

 GDM provides the equivalent of a "login:" prompt for X displays: it
 asks for a login and starts graphical sessions.
 .
 It supports multiple seats and switching between multiple users.
 .
 The greeter is based on the GNOME libraries and applications, and its
 look and design are the same as those of a GNOME session.
 .
 This package contains header and development files.