LR5: How do I switch the white border around an image off in "Lightning Damp" Mode?

Question to LR5:
How do I turn that white border off, when I am switching the "view/Lighting Mode" (button "L" ) to damp?
(sorry I am using german version and I hope the terms are right)

In LR4 there was no border around the picture when going on other lighting, now there is, and I find it quite disturbing. So how can I switch that off?

Thanks for the help