python tkinter滚动条不起作用_滚动条tkinter不滚动

#declare gui object and classes

app = Tk() #creates instance of Tk()

app.title('Check sort DCA') # sets title of gui

#---------------------------------------

def keepSuggested(): #button press actions

es.JournalOut('test2')

def UseNew():

es.JournalOut('test1')

#------------------------------

frame=Frame(app,width=500,height=500)

frame.grid(row=0,column=0)

canvas=Canvas(frame,bg='#FFFFFF',width=500,height=500,scrollregion=(0,0,500,500))

hbar=Scrollbar(frame,orient=HORIZONTAL)

hbar.pack(side=BOTTOM,fill=X)

hbar.config(command=canvas.xview)

vbar=Scrollbar(frame,orient=VERTICAL)

vbar.pack(side=RIGHT,fill=Y)

vbar.config(command=canvas.yview)

canvas.config(width=500,height=500)

canvas.config(xscrollcommand=hbar.set, yscrollcommand=vbar.set)

canvas.pack(expand=True,fill=BOTH)

spacer1 = Label(canvas, text='|')

spacer2 = Label(canvas, text='|')

spacer3 = Label(canvas, text='|')

spacer4 = Label(canvas, text='|')

spacer5 = Label(canvas, text='|')

Chan_Num = Label(canvas,text='Channel Number')

Chan_Name = Label(canvas, text='Channel Name')

NewChan_Num = Label(canvas, text='New Channel Number')

Set_Title = Label(canvas, text='Set New')

std_Num=Label(canvas, text='Standard Channel Number')

std_Name = Label(canvas, text='Standard Channel Name')

Chan_Num.grid(row=0, column=0)

spacer1.grid(row=0, column=1)

Chan_Name.grid(row=0, column=2)

spacer2.grid(row=0, column=3)

NewChan_Num.grid(row=0, column=4)

spacer3.grid(row=0, column=5)

Set_Title.grid(row=0, column=6)

spacer4.grid(row=0,column=7)

std_Num.grid(row=0,column=8)

spacer5.grid(row=0,column=9)

std_Name.grid(row=0,column=10)

n=0

i = 0 # loops through all channel numbers to get print table value.

while i < nchan: # prints out all present channels with index and channel number and title #populates tables

ch_name = tsin.GetChanTitle(i)

ch_num = tsin.GetChanNumber(i)

ch_name_list = Label(canvas, text=ch_name )

ch_num_list = Label(canvas, text=str(ch_num))

ch_name_list.grid(row=i + 1, column=2)

ch_num_list.grid(row=i + 1, column=0)

UserInput=StringVar()

EntryBox= Entry(canvas, textvariable = UserInput)

EntryBox.grid(row=i+1,column=4 )

i = i + 1

j=0

while j< len(CorrectChannels):

stdList= CorrectChannels[j]

stdListNum = j

std_ch_num= Label(canvas,text=stdListNum+1)

std_ch_name = Label(canvas,text=stdList)

std_ch_name.grid(row=j+1, column=10)

std_ch_num.grid(row=j+1, column=8)

j=j+1

#build gui elements

Buttonnew = Button(canvas, text='Set Channels', bg='blue', fg='white',command=UseNew)

Buttonnew.grid(row=1, column=6)

Buttonkeep = Button(canvas, text='keep channels', bg='blue', fg='white', command=keepSuggested)

Buttonkeep.grid(row=2, column=6)

app.mainloop()

当我运行tkinter代码python代码时，我得到了一个没有滚动功能的滚动条，我的所有小部件都在画布中，并且显示正确，但是需要滚动才能看到它们，这段代码生成了一个滚动条，但是它不起作用。