__init__ (
        self,
        parent,
        radius='.5i',
        command=None,
        initAngle=0.0,
        zeroAxis='x',
        rotDir='counterclockwise',
        fill=None,
        outline='black',
        line='black',
        )

button_press_cb ( self,  event )

button_release_cb ( self,  event )

event_angle ( self,  event )

pointer_drag_cb ( self,  event )

set_angle (
        self,
        a,
        doCallback=1,
        )