Symbol line types

[Anonymous]

Why is it that when using a symbol line as a polyline the line is distorted at corners, rather than mitred? I have defined a symbol line for a tanking membrane, but it does funny things if it is drawn with a polyline; its not even consistent.

See below the difference between lines and a polyline:

[Anonymous]

Clearly something GS has not fully worked out yet. Symbol line types are a bit quirky.