'Return a tuple of X1,Y1,X2,Y2 coordinates for a
rectangle which encloses the character given by index.
The first two elements of the list give the x and y
coordinates of the upper-left corner of the screen
area covered by the character (in pixels relative
to the widget) and the last two elements give the
width and height of the character, in pixels. The
bounding box may refer to a region outside the
visible area of the window.'

def bbox(self, index):

    return self.tk.call(self._w, 'bbox', index)
