Can I combine Polyline materials?

Is it possible to easily combine Polyline materials? For example, can I have an outlined arrow that combines both PolylineOutline and PolylineArrow materials? I checked the Fabric wiki, doc, and Sandcastle examples and couldn’t figure out if there was a way to do it (so I assume it’s not a simple task).

I haven’t tried it, but it’s probably going to take some tweaks to support composite materials for polylines given the use of the varying width variable. Submit an issue. In the meantime, a custom material won’t be too hard to write, and might be the only way to get the desired effect, depending on what it is, e.g., outline on polyline, but solid color on arrow, etc.