Grey tracer on Blackberry Priv screen?

[AC Question]

Grey tracer on Blackberry Priv screen

When my girlfriend slides her finger across the screen of her Blackberry Priv she sees a very thin grey line follow her finger around in the direction she moves her finger. This just now started appearing. No updates have been installed prior and she's running Android 5.1.1. I have never seen anything like this on any Android device I have owned.

 

[Jonneh]

Are there coordinates at the top of the screen?

Settings --> Developer Options --> Pointer Location (turn off)

It sounds like that's checked in the on position for some reason?