python写的一个文本编辑器

代码如下:
#!/usr/bin/env python
#-*- coding: utf-8 -*-
#=============================================================================
#     FileName:
#         Desc:
#       Author: ToughGuy
#      Version: 0.0.1
#   LastChange: 2013-02-20 14:52:11
#      History:
#=============================================================================

from Tkinter import *
import tkMessageBox,tkFileDialog
import platform

# nl = os.linesep

def openfile():
    global filename             # 使用global声明为全局变量，方便后边的程序调用
    systype = platform.system() # 判断系统类型
    if systype == 'windows':
        basedir = 'c://'
    else:
        basedir = '/'
    filename = tkFileDialog.askopenfilename(initialdir=basedir)
    try:
        fobj_r = open(filename, 'r')
    except IOError, errmsg:
        print '*** Failed open file:', errmsg
    else:
        editbox.delete(1.0, END)
        for eachline in fobj_r:
            editbox.insert(INSERT, eachline)
        fobj_r.close()

def savefile():
    save_data = editbox.get(1.0, END)
    try:
        fobj_w = open(filename, 'w')
        fobj_w.writelines(save_data.encode('utf-8'))
        fobj_w.close()
        tkMessageBox.showinfo(title='提示',
                message='保存成功')
    except IOError, errmsg:
        tkMessageBox.showwarning(title='保存失败', message='保存出错    ')
        tkMessageBox.showwarning(title='错误信息', message=errmsg)
    except NameError:
        tkMessageBox.showwarning(title='保存失败', message='未打开文件')
def showlinenum():
    tkMessageBox.showinfo(title='提示',
            message='这个功能作者现在不会写,放这里装饰用的.')
def destroy_ui(ui):
    ui.destroy()

def aboutauthor():
    author_ui = Toplevel()