v6.5.0 adds a 'broad' style for curved (i.e. bezier, non-linear) map links, set via the Document Inspector's Links tab. The link tapers in width from wider at the source to narrower at the destination. Dash/dot settings are applied as a border in broad mode, combining in patterns as for a normal narrow link. The border is drawn in the link's colour and the link's fill is in a lighter tint of that colour.
The broad setting applies to all links of a given type, although it can be over-ridden as a per-link style as with other settings.