如何将kivy小部件推送到屏幕顶部

Question

Am having a hard time trying to align my widgets to the top of window in kivy, here is the pictorial represenation. My expectation is that adding an empty widget at the bottom would push the widgets to the top of the screen but it only gets to the middle of the screen. Any guidance will be helpful.

Layout

.kv file

#:import utils kivy.utils
#: import Window kivy.core.window.Window

<FlatButton@ButtonBehavior+Label>:
    font_size: 14

<PosWindow>:
    id: main_win
    orientation: 'vertical'
    canvas.before:
        Color:
            rgb: utils.get_color_from_hex('#ffffff')
        Rectangle:
            size: self.size
            pos: self.pos

    BoxLayout:
        spacing: 0
        orientation: 'vertical'

    #THE BEGINNNING OF THE TOP BAR
    BoxLayout:
        size_hint_y: None
        height: 30

        Label:
            text: 'HEADER POSITION'
            size_hint_x: .6
            bold: True
            color: (1,1,1,1)
            canvas.before:
                Color:
                    rgb: utils.get_color_from_hex('#5B2437')
                Rectangle:
                    size: self.size
                    pos: self.pos


        Label:
            text: 'The Name'
            size_hint_x: .4
            height: 30
            bold: True
            color: (1,1,1,1)
            canvas.before:
                Color:
                    rgb: utils.get_color_from_hex('#5B2437')
                Rectangle:
                    size: self.size
                    pos: self.pos
    # THE END OF THE TOP BAR




    #THE BEGINNING OF THE SECOND WAVE FULL
    BoxLayout:
        id: current
        size_hint_y: None
        height: 50
        canvas.before:
            Color:
                rgba: (1,1,1, 1)
            Rectangle:
                size: self.size
                pos: self.pos
        Button:
            text: 'Current Item:'
            background_normal: ''
            background_color: (.06, .32, .32, 1)
            size_hint_x: .4
        Button:
            id: cur_product
            text: 'Default Product'
            background_normal: ''
            background_color: (.06, .4, .4, 1)
        Button:
            id: cur_price
            text: '0.00'
            background_normal: ''
            background_color: (.06, .65, .65, 1)
            size_hint_x: .2

    Widget: #To place everything at the top of the screen
    #THE END OF THE SECOND WAVE FULL



    #SEARCH FOR A PRODUCT
    BoxLayout:
        id: current
        orientation: 'horizontal'
        size_hint_y: None
        height: 50
        canvas.before:
            Color:
                rgba: (1,1,1, 1)
            Rectangle:
                size: self.size
                pos: self.pos

        BoxLayout:
            size_hint_x: .4
            id: searchBox
            canvas.before:
                Color:
                    rgba: (.06, .75, .35, 1)
                Rectangle:
                    size: self.size
                    pos: self.pos


        BoxLayout:
            size_hint_x: .6
            id: previewBox
            canvas.before:
                Color:
                    rgba: (.06, .35, .85, 1)
                Rectangle:
                    size: self.size
                    pos: self.pos

    Widget:

Answer 1

I found that as a little, I had to remove the first BoxLayout first the empty widgets except for the last boxlayout.

#:import utils kivy.utils
#: import Window kivy.core.window.Window

<FlatButton@ButtonBehavior+Label>:
    font_size: 14

: id: main_win orientation: 'vertical' canvas.before: Color: rgb: utils.get_color_from_hex('#ffffff') Rectangle: size: self.size pos: self.pos

#THE BEGINNNING OF THE TOP BAR
BoxLayout:
    size_hint_y: None
    height: 30

    Label:
        text: 'HEADER POSITION'
        size_hint_x: .6
        bold: True
        color: (1,1,1,1)
        canvas.before:
            Color:
                rgb: utils.get_color_from_hex('#5B2437')
            Rectangle:
                size: self.size
                pos: self.pos


    Label:
        text: 'The Name'
        size_hint_x: .4
        height: 30
        bold: True
        color: (1,1,1,1)
        canvas.before:
            Color:
                rgb: utils.get_color_from_hex('#5B2437')
            Rectangle:
                size: self.size
                pos: self.pos


#THE BEGINNING OF THE SECOND WAVE FULL
BoxLayout:
    id: current
    size_hint_y: None
    height: 50
    canvas.before:
        Color:
            rgba: (1,1,1, 1)
        Rectangle:
            size: self.size
            pos: self.pos
    Button:
        text: 'Current Item:'
        background_normal: ''
        background_color: (.06, .32, .32, 1)
        size_hint_x: .4
    Button:
        id: cur_product
        text: 'Default Product'
        background_normal: ''
        background_color: (.06, .4, .4, 1)
    Button:
        id: cur_price
        text: '0.00'
        background_normal: ''
        background_color: (.06, .65, .65, 1)
        size_hint_x: .2
#THE END OF THE SECOND WAVE FULL



 #SEARCH FOR A PRODUCT
BoxLayout:
    id: current
    orientation: 'horizontal'
    size_hint_y: None
    height: 50
    canvas.before:
        Color:
            rgba: (1,1,1, 1)
        Rectangle:
            size: self.size
            pos: self.pos

    BoxLayout:
        size_hint_x: .4
        id: searchBox
        canvas.before:
            Color:
                rgba: (.06, .75, .35, 1)
            Rectangle:
                size: self.size
                pos: self.pos


    BoxLayout:
        size_hint_x: .6
        id: previewBox
        canvas.before:
            Color:
                rgba: (.06, .35, .85, 1)
            Rectangle:
                size: self.size
                pos: self.pos

Widget: