I got an idea, however I think is between impossible or long time to able to realize the capability of manager,
Lets just say we sometimes use arrow keys to navigate if the touchpad failed and there is no workable mouse around.
Press Left Arrow key to go left of the box automatically shows you the list
Then type to filter down the account needed, and press enter to select
Then Press downward arrowkey to go another line depending whether is field text or drop down list type (this will behave like the second picture from above.