I had a little time to kill so I decided to update the Lens of Truth. In most ZFGs I have seen the Lens of Truth reveals everything in the view. In the Original OOT however, you might recall that only the portion of objects that are seen through the center of the screen (where the lens actually is) is made visible, or invisible as the case might be. So having played around with surfaces for a bit I managed to recreate that effect.
So now when you use the Lens of Truth the view portion of the lens starts in the middle of the screen and then you can press your up,down,left,right keys to scan the room for secrets. As you can see in the screen shot the secret passage at the bottom of the screen is slightly faded out because that is where the edge of the lens was when I took the snap shot. It took a bit of work to get it working, but I am pretty happy with it.