How to increase number of found users when @mention them within comment

[Wilfried Möller]

If mentioning a user within a comment by @ it only will show the first 5 found users. Not all available users with entered name are shown.

How this number can be increased?

Or even better, how the same functionality from choosing a user as assignee can be used for mentioning a user?

For the assignee all users will be shown supported by a drop-down-box (scroll functionality) if too many users found than can be displayed at once.

[Brant Schroeder]

There is no way to expand the number that is shown or change how it works. but as you type it will narrow the selection down.  You can also use email since it is unique to the user.