This is clearly a bug in canvasdraw arrow(s)
I will have to look into this…and see if there are any other mis behaviours with dashing,,,
(other primitives like lines,hlines,segments etc do not show this error)
helas this is not a bug of canvasdraw, but it seems that the html5 canvas implementation of dashing is somewhat troublesome.
The dashing may even be different on different browsers
For now there is no -easy- way to correct this in canvasdraw.