title: Kivy Labels are all acting together when one of them is touched
body: <p>I am a beginner trying to make a Sudoku game with kivy. I created my own Buttons class which inherits from Kivy's Button class so I can define properties that all labels have in common, but I am running into an issue where if I press one of the labels, they all act together.</p>
  <pre><code>from kivy.app import App
  from kivy.uix.floatlayout import FloatLayout
  from kivy.uix.label import Label
  
  
  class SudokuLabel(Label):
      # Define colors
      bg_color = (250 / 255, 250 / 255, 250 / 255)
      font_color = (200 / 255, 200 / 255, 200 / 255)
      touch_bg_color = (58 / 255, 110 / 255, 223 / 255, 0.9)
      touch_font_color = (250 / 255, 250 / 255, 250 / 255)
      value = &quot;&quot;
  
      def __init__(self, value, **kwargs):
      super(SudokuLabel, self).__init__(**kwargs)
      self.value = value
      self.color = self.font_color
      self.font_size = 32
      self.size_hint = 1/10, 1/18  # Grid fills 90% of screen horizontally, and 50% vertically
      
  def on_touch_down(self, touch):
      self.color = self.touch_font_color
  
  def on_touch_up(self, touch):
      self.color = self.font_color
  
  def __repr__(self):
      return str(self.value)
  </code></pre>
  <p>I suspected that the problem is with the way I am inheriting from the Label class, so I made another class to inherit from &quot;SudokuLabel&quot; where I define the &quot;one_touch_down&quot; method but that did not work. Any help is appreciated.</p>
  <p>Also, I am not using a .kv file because I am creating the Sudoku sheet labels in a for loop, and I don't know if I can do that with the kv language. So please provide a python response if you have one.</p>