Button presses counter
You defined a CENTER constant. Could you not do the same with SKY_BLUE, instead of the comment?

super().__init__(*SKY_BLUE)





def update_counter(self):
    self.text.element.text = str ( int(self.text.element.text)+1 )
    self.text.element.position = 320, 240



Using the text label as your data model is cumbersome. Keep an internal count instead of parsing the count back out of the UI.

Do you really need to re-center the label after each change? If so, explain why in a comment, and reuse a CENTER constant.




def on_mouse_press(self, x, y, buttons, modifiers):
    if x &gt; 241 and x &lt; 399 and y &gt; 161 and y &lt; 319 \
    and self.b_released and buttons &amp; pyglet.window.mouse.LEFT:



Python supports double-ended inequalities like 241 &lt; x &lt; 399. I'm having a hard time understanding why the hot zone is defined with those particular bounds.  I'm guessing that you are hard-coding some coordinates that should be automatically determined.