doc: added example, module docs for behaviors/togglebutton.py

Author: Zen-CODE

kivy/uix/behaviors/togglebutton.py

@@ -1,4 +1,45 @@
-'''See :class:`ToggleButtonBehavior` for details.
+'''
+ToggleButton Behavior
+=====================
+
+The :class:`~kivy.uix.behaviors.togglebutton.ToggleButtonBehavior`
+`mixin <https://en.wikipedia.org/wiki/Mixin>`_ class provides
+:class:`~kivy.uix.togglebutton.ToggleButton` behavior. You can combine this
+class with other widgets, such as an :class:`~kivy.uix.image.Image`, to provide
+alternative togglebuttons that preserve Kivy togglebutton behavior.
+
+For an overview of behaviors, please refer to the :mod:`~kivy.uix.behaviors`
+documentation.
+
+Example
+-------
+
+The following example adds togglebutton behavior to an image to make a checkbox
+that behaves like a togglebutton::
+
+    from kivy.app import App
+    from kivy.uix.image import Image
+    from kivy.uix.behaviors import ToggleButtonBehavior
+
+
+    class MyButton(ToggleButtonBehavior, Image):
+        def __init__(self, **kwargs):
+            super(MyButton, self).__init__(**kwargs)
+            self.source = 'atlas://data/images/defaulttheme/checkbox_off'
+
+        def on_state(self, widget, value):
+            if value == 'down':
+                self.source = 'atlas://data/images/defaulttheme/checkbox_on'
+            else:
+                self.source = 'atlas://data/images/defaulttheme/checkbox_off'
+
+
+    class SampleApp(App):
+        def build(self):
+            return MyButton()
+
+
+    SampleApp().run()
 '''
 
 __all__ = ('ToggleButtonBehavior', )
@@ -10,8 +51,9 @@
 
 class ToggleButtonBehavior(ButtonBehavior):
     '''This `mixin <https://en.wikipedia.org/wiki/Mixin>`_ class provides
-    :class:`~kivy.uix.togglebutton.ToggleButton` behavior. Please see
-    the :mod:`~kivy.uix.togglebutton` module documentation for more information.
+    :mod:`~kivy.uix.togglebutton` behavior. Please see the
+    :mod:`togglebutton behaviors module <kivy.uix.behaviors.togglebutton>`
+    documentation for more information.
 
     .. versionadded:: 1.8.0
     '''