enable/disable widgets with checkbox(TKinter)

[jwsacksteder at ramprecision.com]

I want to have a check box that can optionally disable a text input field in
the same dialog. I am asking the user to input the start and end of a range
and there needs to be a check box to select all items. When the checkbox
changes state, I want to ghost-out the input fields.

A rough approximation of the situation follows.

class mystuff(Frame):
    def __init__(self,parent=None):
        Frame.__init__(self,parent)
        self.CheckMode = IntVar()
        
        self.mode_label = Label(self, text='All Line Items?',
borderwidth='5')
        self.mode_box = Checkbutton(self,
width='1',variable=self.CheckMode,command=self.FlipState)
        self.input_label = Label(self, text='Input Name', borderwidth='5')
        self.input_box = Entry(self, width='3')

        self.pack()

    def FlipState(self):
        #This does not work!
        self.input_box.disable()
        print "variable is", self.LineItemMode.get()