First of all, thanks for the great product and support.
We purchased the highcharts base license and are currently investigating if we would like to get the highmaps extension aswell.
I found out the following "flight routes" chart:
Which is very close to one of our use case for a custom map.
I would like a slight modification however, and did not find much documentation on the "chart.path" property.
More broadly, I do not find much documentation on how to draw your custom svg elements on these maps.
Example I used
I would like to add ARROWHEADS to these lines to show the direction of the fluxes.
Also, the curvature on the lines is probably not needed for our use case but I did not really research how to modify your the custom functrion from the flight-routes example.