I have no way to get proof of this, becuase it's not something that appeared, it's what DIDN'T APPEAR! I was setting up an area to show off all the features of 1.6.1 to my friend, and when i set up some signs on the fences, the GUI to enter text on the sign doesn't pop up. I wish i had some way to get photographic evidence, but sadly, not even in-game snapshots can help. You'll have to take my word for it and check the bug.