After an evaluation, GNOME has moved from Bugzilla to GitLab. Learn more about GitLab.
No new issues can be reported in GNOME Bugzilla anymore.
To report an issue in a GNOME project, go to GNOME GitLab.
Do not go to GNOME Gitlab for: Bluefish, Doxygen, GnuCash, GStreamer, java-gnome, LDTP, NetworkManager, Tomboy.

Some mockups can be seen here

https://github.com/gnome-design-team/gnome-mockups/tree/master/overlay-help

An implementation is in https://git.gnome.org/browse/gtk+/log/?h=wip/matthiasc/help-overlay

Here is the design page: https://wiki.gnome.org/Design/OS/HelpOverlay#Tentative_Design