I somehow turned on a black outline around anything selected - most annoying. Can anybody tell me where to control this ? I don't know what Apple CALLS this so I can't find it to change it. Help ? ? - thanks very much.
You can follow below steps to get rid of this problem.
Click on the Apple (logo) menu
open System Preferences.
you will see the option of "highlight color"
Select whatever you like(don't choose black)
Let me know.