Jump when an object becomes physical

[Yichard]

This issue plagued my trains from the start. They use a physical slider in a U shaped track.
I finally found an hypothesis: it would be that, when the slider becomes physical, it first deals with the convex hull of the track, before the prim shape is loaded from the server. This produces a disengagement force, hence the jump.
The solutions would be:

• To start the physics only when the prim shape is received. (or if the prim shape fetch is timing out)
• To have a function requesting the prim shape of an object, something like hlStartPhysicalShape(object). The vehicle playing this function would be aware of the indicated prim shape, at least until it loses contact with it.

This function would also be handy to avoid another bug: the train being stuck when it comes on a new track element. Or derailling ifin a curve if the curve is in a region crossing. These issues may have the same cause.