But it will also work if you start to enter the display name into the field.

It doesn't accept the display name.

Error message: We couldn't find the recipient's name.

Works for me both on Elgg 1.X and current 2.0 beta. But it must be noted that only users who are friends are offered by the autocomplete feature. If it doesn't work for you maybe some 3rd party plugin is changing the default behaviour.

"But it must be noted that only users who are friends are offered by the autocomplete feature".

Thanks, iionly. I overlooked that :)

Still there is a problem. Wherever I click on a member icon (be it under Newest Members or on Blogs), It first shows a block in the following format:

displayname

@username

Only when I click on it, I reach the person's profile. And the "@username" is even visible to the public! How to get rid of this element?

I found out. I haven't entered the whole path :)

version of Elgg?

Version 1.7.x