def __init__(self, *args, **kwargs):
"""
CheckBox is a kind of button, and thus will also generate 'click' and
'default' events when clicked. But in addition, each CheckBox has a
Boolean attribute on, which is toggled each time the box is clicked.
The state of the CheckBox can be altered by assigning to this
attribute.
"""
AbstractToggleButton.__init__(self, *args, **kwargs)