为什么我不能使用TKinter正确切换到新框架？

Question

I am using a container class in TKinter to start with a Menu screen and be able to switch to one of two other screens when necessary. It isn't quite working correctly and I'm not sure why.

Here is what my main menu screen looks like:

http://i62.tinypic.com/2nhoju0.jpg (won't let me post images yet)

When I click New Game, it looks like this:

http://i57.tinypic.com/x3tglg.jpg (won't let me post images yet)

Clearly, the new game and continue buttons are not supposed to be there, and there should only be one quit button. There should also be a label at the top kinda like the main menu screen.

Can anyone tell me why this is happening?

Here is the relevant code:

class Battleship():
    def __init__(self, root):
        self.root = root
        self.pages = {}

        container = Frame(root)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        for P in (MainMenu, ShipSelect, BattleScreen):
            frame = P(container, self)
            frame.grid(row=0, column=0, sticky="nsew")
            self.pages[P] = frame
        self.show_frame(MainMenu)

    def show_frame(self, cont):
        frame = self.pages[cont]
        frame.tkraise()

class MainMenu(Frame):
    def __init__(self, parent, controller):
        Frame.__init__(self, parent)
        label = Label(self, text="Welcome to PyBattleship!", font=LARGE_FONT)
        label.pack(pady=10,padx=10)


        button1 = Button(root, text='New Game', width=13, command=lambda :controller.show_frame(ShipSelect))
        button1.pack()
        button2 = Button(root, text='Continue Game', width=13)
        button2.pack()
        button3 = Button(root, text='Quit', width=13, command=lambda controller=controller:controller.root.destroy())
        button3.pack()

class ShipSelect(Frame):
    def __init__(self, parent, controller):
        Frame.__init__(self, parent)
        self.root = root
        label = Label(self, text="Please place your ships", font=LARGE_FONT)

        button1 = Button(self, text='Quit', width=13, command=lambda    controller=controller:controller.root.destroy())
        button1.pack()

root = Tk()
root.title('Py-Battleship')
sheet = Battleship(root)
root.mainloop()

Answer 1

I just realized that I was still using 'root' for the button widgets in MainMenu. When I changed the 'roots' to 'self' and added padding to the label in ShipSelect, it seems to work.

class MainMenu(Frame):
    def __init__(self, parent, controller):
        Frame.__init__(self, parent)
        label = Label(self, text="Welcome to PyBattleship!", font=LARGE_FONT)
        label.pack(pady=10,padx=10)


        button1 = Button(self, text='New Game', width=13, command=lambda controller=controller:controller.show_frame(ShipSelect))
        button1.pack()
        button2 = Button(self, text='Continue Game', width=13)
        button2.pack()
        button3 = Button(self, text='Quit', width=13, command=lambda controller=controller:controller.root.destroy())
        button3.pack()



class ShipSelect(Frame):
    def __init__(self, parent, controller):
        Frame.__init__(self, parent)
        label = Label(self, text="Please place your ships", font=LARGE_FONT)
        label.pack(pady=10,padx=10)

        button1 = Button(self, text='Quit', width=13, command=lambda controller=controller:controller.root.destroy())
        button1.pack()

Answer 2

Using a mixture of grid and pack in tkinter is never a good idea, which is one of the reasons your code might be having unpredictable results. Secondly, you are trying to pack the buttons to the root window, rather than one of the frames you have created.