from kivy.uix.button import Button

class MultiLineButton(Button):
    def __init__(self, **kwargs):
        super(MultiLineButton, self).__init__( **kwargs)
        self.markup = True
        self.text_size = self.size
        self.bind(size= self.on_size)
        self.bind(text= self.on_text_changed)
        self.size_hint_y = None # Not needed here

    def on_size(self, widget, size):
        self.text_size = size[0], self.height
        self.padding_x = 20
        self.valign = 'middle'
        self.texture_update()
        if self.size_hint_y == None and self.size_hint_x != None:
            self.height = max(self.texture_size[1], self.line_height)
        elif self.size_hint_x == None and self.size_hint_y != None:
            self.width  = self.texture_size[0]

    def on_text_changed(self, widget, text):
        self.on_size(self, self.size)
