Show display name toghther with user name and email

[aostrow]

Is there an existing issue for this?

• I searched for a similar issue and didn't find a suitable one.

What is your improvement proposal all about?

Similar to #2267, there are different places and cases where only the user name is used. Sometimes, together with the email. It would be more useful to show the full name/display name instead, or together with it.

Some (probably not a full set) cases are:

• group membership

• name in the notification mails, e.g. XXX: Created (ID...)

How does the current implementation works and what is wrong about it?

see above

How should the (part of the) feature be implemented?

nicely