Kivy: confirmation popup dialog

confirmpopup.kv

<-ConfirmPopup>:
	GridLayout:
		cols: 1
		padding: '12dp'
		pos_hint: {'center': (0.5, 0.5)}
		size_hint_x: 0.66
		size_hint_y: None
		height: self.minimum_height
		
		canvas:
			Color:
				rgba: root.background_color[:3] + [root.background_color[-1] * root._anim_alpha]
			Rectangle:
				size: root._window.size if root._window else (0, 0)
			
			Color:
				rgb: 1, 1, 1
			BorderImage:
				source: root.background
				border: root.border
				pos: self.pos
				size: self.size
	
		Label:
			text: root.text
			size_hint_y: None
			height: self.texture_size[1] + dp(16)
			text_size: self.width - dp(16), None
			halign: 'center'
		
		BoxLayout:
			size_hint_y: None
			height: sp(48)
			
			Button:
				text: root.cancel_text
				on_press: root.cancel()
			Button:
				text: root.ok_text
				on_press: root.ok()

confirmpopup.py

from kivy.properties import StringProperty
from os.path import join, dirname
from kivy.lang import Builder
from kivy.uix.popup import Popup

Builder.load_file(join(dirname(__file__), 'confirmpopup.kv'))


class ConfirmPopup(Popup):
	text = StringProperty('')
	
	ok_text = StringProperty('OK')
	cancel_text = StringProperty('Cancel')
	
	__events__ = ('on_ok', 'on_cancel')
	
	def ok(self):
		self.dispatch('on_ok')
		self.dismiss()
	
	def cancel(self):
		self.dispatch('on_cancel')
		self.dismiss()
	
	def on_ok(self):
		pass
	
	def on_cancel(self):
		pass