kivytimer.kv

#:kivy 1.0.9
<KivyTimer>:
    BoxLayout:
        orientation: 'vertical'
        pos: root.pos
        size: root.size

        Label:
            text: str(root.left_time)
            font_size: 100

        BoxLayout:
            orientation: 'horizontal'
            size_hint: 1.0, 0.3

            Button:
                text: '+1 minute'
                font_size: 16
                on_press: root.on_command('+1 minute')

            Button:
                text: 'Stop' if root.is_countdown else 'Start'
                font_size: 16
                on_press: root.on_command('start/stop')

            Button:
                text: 'Reset'
                font_size: 16
                on_press: root.on_command('reset')

        # ボタン追加 
        BoxLayout:
            orientation: 'horizontal'
            size_hint: 1.0, 0.3

            Button:
                text: '+10 second'
                font_size: 16
                on_press: root.on_command('+10 second')

            Button:
                text: '+30 second'
                font_size: 16
                on_press: root.on_command('+30 second')

            Button:
                text: '+3 minute'
                font_size: 16
                on_press: root.on_command('+3 minute')