Hi Speedy - about the scaling rail, there are 2 problems here.

First, a scaling rail should be smooth throughout, the one you have here comes to a sharp point in the middle which will probably cause a kind of strange lump in the surface at that point. If you want it to come to a sharp point there, then you will need to do the sweep in multiple pieces instead of all in one piece.

It is possible to smooth out the sharp point in your scaling rail by turning on points and then selecting and deleting the sharp point.

Then the second problem is that for the scaling rail to work well, it needs to cover the full extent of the sweep. In this case your scaling rail does not fully extend to the ends of the sweep, it stops at a point internal to the sweep.

I have illustrated that here by extending a perpendicular line along your profile - you can see that there is a gap there between that plane and the end of your scaling rail.



It is ok if your scaling rail shoots out farther than the sweep (in fact it is a good idea to go ahead and make it extend further to be safe), but if it does not cover the entire range of the sweep the sweep will revert to regular non-scaling-rail behavior in those areas.


About surface extension - I'd like to add this in the future but I'm sorry I don't think I will be able to do it in time for the 1.0 version, this will have to wait until the 2.0 version. The other way to do this right now is to construct a new surface using the edge of an existing surface as one of the curves. For example do a one-rail sweep using the edge of a surface to construct a new one that is touching it.

About extend and history - this was a bug, I have fixed it for the next beta release. So for example if you have extruded a curve and then extend the curve, in the next beta the extrusion will also update.

Is there something else that you want to know about history other than that extend bug? If so please let me know.

- Michael