Wire arrowhead parameters defaults

[reinago]

Hi,

I just discovered this library and found it quite neat for drawing flow charts. I now have a chart where multiple boxes join in a subsequent one. I chose one of them to form the backbone and just attached the second "from the side":

result:

with Drawing() as d:
    width = 5.5
    height = 1
    arrowlen = d.unit / 4
    data_bg = "#ccecff"
    process_bg = "#ffbfbf"

    d.config(font="sans", lw=2)
    flow.Box.defaults["fill"] = data_bg
    flow.Box.defaults["w"] = width
    flow.Box.defaults["h"] = height
    flow.Box.defaults["minsize"] = (width, height)
    flow.RoundBox.defaults["fill"] = process_bg
    flow.RoundBox.defaults["w"] = width
    flow.RoundBox.defaults["h"] = height
    flow.RoundBox.defaults["minsize"] = (width, height)
    flow.Arrow.defaults["arrowwidth"] = 0.3
    flow.Arrow.defaults["arrowlength"] = 0.3

    # print(flow.Box.defaults)
    db = flow.Box().label("first").drop("S")
    flow.Arrow().down(arrowlen)
    aq = flow.RoundBox().label("second")

    flow.Box().at(db.W, -3.5, height/2).label("side")
    flow.Line().down(arrowlen + height / 2)
    flow.Wire(arrow="->").to(aq.W)

This is exactly what I want (layout-wise). However, the Wire I use to make the elbow connection seems to spawn some Segments internally that do not care about the changed arrowwidth/length defaults, so the arrowheads have different size. I can work around this by just chaining an Arrow to the respective anchor of aq, but where should the default go for this to work? Is this a bug or intentional?