I am having issues with this as well. You have to buy a glass screen protector that is smaller than the screen itself. The 2nd screen on my phone is curved and not flat, therefore causing a halo effect halfway on the 2nd screen.
I bought the one suggested on the other glass screen protector topic [super guardz] and I bought v10 glass ones which are exactly the same size as the super guardz and both leave halos.. at at least for me.