Button:
                id: recul
                markup: True
                background_color: (0, 1.2, 0, 1)
                font_size: "18sp"
                text: '[b]<<<[/b]'
                on_press: root.do_back_forward(-1)
                on_release: root.do_end()
            Button:
                id: avance
                markup: True
                background_color: (0, 1.2, 0, 1)
                font_size: "18sp"
                text: '[b]>>>[/b]'
                on_press: root.do_back_forward(1)
                on_release: root.do_end()