Can't change emblems in Caja. (mate 16.10 beta)
This one is very easy to find.
Just open Caja file manager and try to set an emblem as background. It does the "action" of drag and dropping the texture but it is not set (keeps white), also if you click on any texture there is a weird animation of those traveling from the left corner of the screen.
Using Daily Build from 23/sept/2016. Ubuntu Mate 16.10.