'`' (grave) will fade to 0 and '0' will fade to 100%.

    If mouse_bindings is true, the following mouse bindings will be

    installed: Right clicking toggles muting.  The mouse wheel will

    raise or lower the volume.  Shift-mouse wheeling will cause a more

    precise volume adjustment.  Control-mouse wheeling will cause a

    longer fade."""

    def __init__(self, var, wheel_step=5, use_fades=1, key_bindings=1,

                 mouse_bindings=1):

        self.use_fades = use_fades # whether increase and decrease should fade

        self.wheel_step = wheel_step # amount that increase and descrease should

                                     # change volume (by default)

        self.fade_start_level = 0

        self.fade_end_level = 0

        self.fade_start_time = 0

        self.fade_length = 1

        self.fade_step_time = 10

        self.fade_var = var

        self.fading = 0 # whether a fade is in progress

        if key_bindings:

            for k in range(1, 10):

                self.bind("<Key-%d>" % k,

            self.bind("<Key-0>", lambda evt: self.fade(100))

            self.bind("<grave>", lambda evt: self.fade(0))

            # up / down arrows

            self.bind("<Key-Up>", lambda evt: self.increase())

            self.bind("<Key-Down>", lambda evt: self.decrease())

        if mouse_bindings:

            # right mouse button toggles muting

            # self.bind('<3>', lambda evt: self.toggle_mute())

            # "NOT ANY MORE!" - homer

            # mouse wheel

            self.bind('<4>', lambda evt: self.increase())

            self.bind('<5>', lambda evt: self.decrease())

            # modified mouse wheel

            self.bind('<Shift-4>', lambda evt: self.increase(multiplier=0.2))

            self.bind('<Shift-5>', lambda evt: self.decrease(multiplier=0.2))

            self.bind('<Control-4>', lambda evt: self.increase(length=1))

            self.bind('<Control-5>', lambda evt: self.decrease(length=1))

        self.last_level = 0 # used for muting

    def fade(self, value, length=0.5, step_time=10):

        """Fade to value in length seconds with steps every step_time

        seconds"""

        self.fade_start_time = time.time()

        self.fade_length = length

        self.fade_start_level = self.fade_var.get()

        self.fade_end_level = value

        self.fade_step_time = step_time

        self.fading = 1

        self.do_fade()

    def do_fade(self):

        """Actually performs the fade for Fadable.fade.  Shouldn't be called

        directly."""

        now = time.time()

        elapsed = now - self.fade_start_time

        complete = elapsed / self.fade_length

        complete = min(1.0, complete)

        diff = self.fade_end_level - self.fade_start_level

        newlevel = (complete * diff) + self.fade_start_level

        self.fade_var.set(newlevel)

        if complete < 1:

            self.after(self.fade_step_time, self.do_fade)

        else:

            self.fading = 0

    def increase(self, multiplier=1, length=0.3):

        """Increases the volume by multiplier * wheel_step.  If use_fades is

        true, it do this as a fade over length time."""

        amount = self.wheel_step * multiplier

        if self.fading:

            newlevel = self.fade_end_level + amount

        else:

            newlevel = self.fade_var.get() + amount