I removed it from the user interface because I assumed the use was limited, and maybe too complex. If you have use for it I will definitely bring it back in the user interface the next release.
@Dave-R Got it! Thanks Dave...it did seem like overkill to lock both the viewport and the layers, but it seemed like one of my viewports was shifting (even though camera positions weren't changed) and I thought maybe I had been double-clicking into the viewport(s) w/o realizing it. Still not sure what I did, but it seems to be working now.