Hi Alexandre,
(sorry, this reply somehow seems to have got stuck in my mailbox)
When manupulating 3D box from copy of the window I see blue guides offset:
Thanks for reporting this. It is a known issue that unfortunately has been around for a while. As far as I can tell, it is caused by wrong transforms of 3D boxes. It's the second thing on my to-do-list, the first being some very annoying problems with undo/redo that are even more persistent.
I'm currently giving a rewrite to a good deal of the tool's internals, which should hopefully resolve the latter issues so that I can tackle the transforms. After that I suppose the tool should be ready for enabling and more thorough testing by a broader user community.
Since I also need to get my coding activities aligned with the studying for my final examinations, I can't make precise promises regarding the timeline, but of course I'm trying to fix it as soon as I can (and believe me that coding is much more fun than combatting probability spaces, sigma algebras and stochastic processes ;))
I'll keep you and the list posted on any progress. I really hope it's only a matter of one or (at most) two weeks, but again I can't say for sure, I'm afraid (depends on the amount of unexpected problems I encounter).
Best regards, Max
P.S.: Could someone give me a very quick introduction of how transforms generally work in Inkscape and how objects are supposed to handle them? My somewhat vague understanding so far is that a transform is just a matrix representing an affine transformation that is updated (if necessary) when objects are moved or resized. But in what situations does this matrix turn out to be different from the identity matrix (i.e., when can't the transformation just be applied to the objects' coordinates directly?) and what precisely is supposed to happen in the transform methods in this case? Most of them don't even seem to be present for the "regular" shapes such as ellipses, stars, etc. Thanks!