v17 - setlinestyle() fails with strokepath()

[Paolo F Cantoni]

We have decided to rationalise our shapescripts.  That is, making sure that they do the same thing in the same way.
One of the things we allow the user to do is to set their own linestyle via User-Specified Diagram Properties (USDPs). We've done this for a few years (since USDPs were created).
We've discovered, in non-rectangular mode, that if the shape script creates the shape using startpath(); shape functions... endpath(); fillandstrokepath(); the settings work and the shape is drawn as required.
However, if we use startpath(); shape functions... endpath(); strokepath();  i.e. creating a "transparent" shape for linestyles other than "SOLID", the shape disappears! 
This functionality works correctly in v15.2 (we just confirmed that).  The problem came in with v16 - we've confirmed that, too!
NOTE: Just to demonstrate its usual EAUI cantankerousness - the linestyles work fine in Rectangular mode!
Also, there are other defects in shape rendering - related to this problem (again, working under v15.2) - which I'll detail in other posts.

Reported,
Paolo