Kivy: simple separator

separator.kv

<Separator@Widget>:
    size_hint_y: None
    height: dp(6)
    color: 1, 1, 1, 1
    background_image: ''

    canvas:
        Color:
            rgba: root.color
        Rectangle:
            pos: self.pos
            size: self.size
            source: root.background_image