'Create a and return a new canvas with scale markers.'

def createScale(self):

    height = float(self.gheight)
    width = 25
    ymax = self.ymax
    scale = Canvas(self, width=width, height=height, background=self.bg)
    opts = {'fill': 'red'}
    scale.create_line((width - 1), height, (width - 1), 0, **opts)
    for y in range(0, int((ymax + 1))):
        ypos = (height * (1 - (float(y) / ymax)))
        scale.create_line(width, ypos, (width - 10), ypos, **opts)
        scale.create_text(10, ypos, text=str(y), **opts)
    return scale
