Rhino 6 has toolbar group called “New in V6.” One of its buttons is called “Select sub curve.” It looks like selection command button, but it launches new curve editing command called SubCrv.
Hello - SubCrv, in V6 can be used both as a command on its own and as a selection command inside other commands. (e.g. Loft > select curves, including, if you use this tool, subcurves, to loft). As a selection tool it does not have the usual "!: in front of the command so that it does not cancel the running command.
-Pascal
Yes, I knew that and I forgot to mention this fact… I was wrong - this is not a bug.