This thing seem to be unused to me:

        linestyle_map = {
            'solid': '-',
            'dashed': '--',
            'dashdot': '-.',
            'dotted': ':'
        }

I'm not sure if this is on purpose, from git log it seem like it used to be to allow what is now final_boxprops to support the "dotted", "solid" keyword somewhere (not sure where).
If it's not usefull anymore it might be removed I guess.