gistfile1.txt

        Color:                                                                                                                                                                                                                                                          
            rgb: 0.3, 0.3, 0.3                                                                                                                                                                                                                               from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout

from kivy.properties import ListProperty

from kivy.base import runTouchApp


class Node(Widget):                                                                                                                                                                                                                                          
    pass                                                                                                                                                                                                                                                     

class Board(BoxLayout):                                                                                                                                                                                                                                      
    node1_pos = ListProperty([5, 5])                                                                                                                                                                                                                         

root = Builder.load_string('''                                                                                                                                                                                                                               
<Node>:                                                                                                                                                                                                                                                      
    orientation: 'vertical'                                                                                                                                                                                                                                  
    size: 200, 200                                                                                                                                                                                                                                           
    canvas:                                                                                                                                                                                                                                                  
        Color:                                                                                                                                                                                                                                               
            rgb: 0.3, 0.3, 0.3                                                                                                                                                                                                                               
        Rectangle:                                                                                                                                                                                                                                           
            pos: self.pos                                                                                                                                                                                                                                    
            size: self.size                                                                                                                                                                                                                                  
<Board>:                                                                                                                                                                                                                                                     
    node1_pos: node1.pos                                                                                                                                                                                                                                     
    canvas.after:                                                                                                                                                                                                                                            
        Color:                                                                                                                                                                                                                                               
            rgba: 1, 0, 0, 1                                                                                                                                                                                                                                 
        Line:                                                                                                                                                                                                                                                
            points: root.node1_pos[0],root.node1_pos[1],100,100                                                                                                                                                                                              
                                                                                                                                                                                                                                                             
    Node:                                                                                                                                                                                                                                                    
        id: node1                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                             
    Widget:                                                                                                                                                                                                                                                  
                                                                                                                                                                                                                                                             
    Node:                                                                                                                                                                                                                                                    
        id: node2                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                             
Board:                                                                                                                                                                                                                                                       
''')

runTouchApp(root)