I cannot be certain, but it seems to me it is no longer possible to change the sequence of the columns in the Layers panel. I like to have the Layer Color and Current columns as the first two, so I dragged these to the preferred position. But closing and reopening Rhino sees them returned to the default position. I believe earlier Rhino-versions did save the panel layout, but I am not sure. My current version is 5C254.
As a sideline: double clicking a .3dm file in the Finder opens RhinoWIP, not Rhino5.2, does anybody know how to change that?