myapp.kv

#:kivy 1.1.0

Root:
    text_input: text_input
    label_wid: file_info
    label_modified: is_modified

    BoxLayout:
        orientation: 'vertical'
        BoxLayout:
            ScrollView:
                id: offset
                TextInput:
                    id: text_input
                    text: 'Agregue valor ao seu codigo com Python, pois ele nao usa chaves.'
                    multiline: True
                    size_hint: 1, None
                    height: max( (len(self._lines)+1) * self.line_height, offset.height)
                    
        BoxLayout:
            size_hint_y: None
            height: 30
            Button:
                text: 'Abrir...'
                on_release: root.open_dialog()
            Button:
                text: 'Salvar'
                on_press: root.save_dialog()

        BoxLayout:
            size_hint_y: None
            height: 30
            Label:
                id: file_info
                height: 30
                width:300
                halign: 'center'
                text: '--'
                size_hint: (0, 0)
            Label:
                id: is_modified
                height: 30
                halign: 'right'
                text: '--'
                size_hint: (0, 0)
<OpenDialog>:   

    BoxLayout:
        size: root.size
        pos: root.pos
        orientation: "vertical"
        FileChooserListView:
            id: filechooser
                    

        BoxLayout:
            size_hint_y: None
            height: 30
            Button:
                text: "Cancelar"
                on_release: root.cancel()

            Button:
                text: "Abrir"
                on_release: root.load(filechooser.path, filechooser.selection) 

            
<SaveDialog>:
    text_input: text_input
    BoxLayout:
        size: root.size
        pos: root.pos
        orientation: "vertical"
        FileChooserListView:
            id: filechooser
            on_selection: text_input.text = self.selection and self.selection[0] or ''

        TextInput:
            id: text_input
            size_hint_y: None
            height: 30
            multiline: False

        BoxLayout:
            size_hint_y: None
            height: 30
            Button:
                text: "Cancelar"
                on_release: root.cancel()

            Button:
                text: "Salvar"
                on_release: root.save(filechooser.path, text_input.text)