I'm writing some code where the user needs to be able to select a file that the program will run on. I have created a browse button that allows the user to select a file but when you hit 'okay' the rest of the program doesn't realize that there has been an input. The file name should also automatically be entered in he browse bar after the file has been selected. Any suggestions?

```
from Tkinter import *

class Window:       

def __init__(self, master):     

    #Browse Bar
    csvfile=Label(root, text="File").grid(row=1, column=0)
    bar=Entry(master).grid(row=1, column=1) 

    #Buttons  
    y=7
    self.cbutton= Button(root, text="OK", command=master.destroy)       #closes window
    y+=1
    self.cbutton.grid(row=10, column=3, sticky = W + E)
    self.bbutton= Button(root, text="Browse", command=self.browsecsv)
    self.bbutton.grid(row=1, column=3)

#-------------------------------------------------------------------------------------#
def browsecsv(self):
    from tkFileDialog import askopenfilename

    Tk().withdraw() 
    filename = askopenfilename()

#-------------------------------------------------------------------------------------#
import csv

with open('filename', 'rb') as csvfile:
    logreader = csv.reader(csvfile, delimiter=',', quotechar='|')
    rownum=0

    for row in logreader:    
        NumColumns = len(row)        
        rownum += 1

    Matrix = [[0 for x in xrange(NumColumns)] for x in xrange(rownum)] 

csvfile.close()

root = Tk()
window=Window(root)
root.mainloop()  

```