Hi.
Does the Mentions Mod support a member's display name with space character? 
E.g.: "john black"
Or does it support only login or a display name without space character? If yes, then how about adding a feature to support mentions like @"john black", because display name is not always same as members login and one can't always guess it.

Thank you.

I use it on my forums and plenty of my users have names with spaces in, this mod has no problems with them

It supports spaces in usernames just fine. Only the real name can be used, but that can be expanded easily.