leandro_bk, fixed, see here. Alex, not sure, maybe it is already fixed in that same thread? If not, please create a new thread with exact steps on how to reproduce, expected and actual behavior.
Having separate windows is pretty difficult for technical reasons, since Spine uses OpenGL. Probably won't get to do it any time soon.
It's true OS X doesn't have cursor changes. I'd like to implement this and will eventually, but it is trickier than it seems and there are lots of other things to do. Maybe we could indicate the resize a different way, or by drawing our own icons near the mouse.
Jaf, I fixed opening that goblins project in 2.0.17. Note that Spine comes with a newer goblins project, look in the Spine installation directory, in the examples subdirectory.