from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.lang.builder import Builder

Builder.load_string('''
#:import TreeWindow tree_class.TreeWindow
#:import TextableWidget textable_class.TextableWidget


<MainWindow>:
	padding: 10
	spacing: 10
		
	Label:
		text: "Widget that I don't need"
		
	TreeWindow:
	    id: tree_class
			
	TextableWidget:
	    id: textable_class
''')


class MainWindow(BoxLayout):
    pass


class MainApp(App):
    title = "Sandbox"

    def build(self):
        self.main_window =  MainWindow()
        return self.main_window


if __name__ == '__main__':
    MainApp().run()