用tkinter写一个多标签的界面 标签1可以选择并展示某个csv文件的前10行内容 标签2可以选择某个xlsx文件并转换成csv文件

import tkinter as tk
from tkinter import ttk
from tkinter import *
from tkinter import filedialog
import xlrd
import os

class Application(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("多标签界面")
        # set window size
        ws = self.winfo_screenwidth()
        hs = self.winfo_screenheight()
        w = 500
        h = 300
        x = (ws/2) - (w/2)
        y = (hs/2) - (h/2)
        self.geometry('%dx%d+%d+%d' % (w, h, x, y))

        self.defaultFileType = [('csv', '*.csv'), ('all', '*')]
        self.defaultFileType2 = [('xlsx', '*.xlsx'), ('all', '*')]
        self.init_window()

    def init_