What is the bar running down the center of my screen?

[Windows Central Question]

what is the bar running down the centre of my screen? I have a nokia lumia 435

it's making it difficult to read messages, type messages, access stuff. It appears to be a reflection of any screen under it. I got it off somehow once but it came back.

 

[bhtkb]

Re: what is the bar running down the centre of my screen? I have a nokia lumia 435

Can you post a screenshot to make it clearer? Are you talking about an issue or a feature that you want to turn off, I couldnt quite catch.