right
    A: box "Box A" color white fill 0x2a6b3a width 1.2 height 0.5 rad 5px
    move 0.5
    B: box "Box B" color white fill 0x2a4a6b width 1.2 height 0.5 rad 5px
    arrow from A.e to B.w color white thick
    text "label" color 0x888888 at last arrow.c + (0, -0.25)