如何使用 for 循环更新 Tkinter 标签/画布小部件中的文本？

Question

I am having issues in updating text in label as well as in canvas. Updating text in canvas itself was tiresome. Didn't find anything useful.

My project is here - https://github.com/MRDGH2821/Words-Per-Minute-/tree/beta

What I wish to do - Display a paragraph, word by word (with some delay in between)

What I thought while writing the code - Paragraph will be in file. The code will read the paragraph, extract 1st word & put them into label widget. After a delay, 1st word will disappear & 2nd word will be put to display. And so on.

What the code actually does - Instead of showing the whole word, its showing 1st letter of 1st word. I used for loop to update the text displayed in label widget, but it doesn't update/refresh.

Here is the code snippet -

root = tk.Tk()
root.attributes("-fullscreen", True)
root.bind("<F11>", lambda event: root.attributes("-fullscreen", not root.attributes("-fullscreen")))
root.bind("<Escape>", lambda event: root.attributes("-fullscreen", False))
root.bind("<F1>", lambda event: os.exit(0))

w = tk.StringVar()

labelFlash = tk.Label(root, bg='Black', width=root.winfo_screenwidth(), height=root.winfo_screenheight(),
                      anchor="center", text="Sample", fg="White", font="Times " + str(cofg.GetFontSize()), textvariable=w)
labelFlash.pack()
for word in words:
    w.set(word)
    labelFlash.config(text=word)

Answer 1

import tkinter as tk
root = tk.Tk()
root.attributes("-fullscreen", True)
root.bind("<F11>", lambda event: root.attributes("-fullscreen", not root.attributes("-fullscreen")))
root.bind("<Escape>", lambda event: root.attributes("-fullscreen", False))
root.bind("<F1>", lambda event: os.exit(0))

w = tk.StringVar()

labelFlash = tk.Label(root, bg='Black', width=root.winfo_screenwidth(), height=root.winfo_screenheight(),
                      anchor="center", text="Sample", fg="White", font="Times " , textvariable=w)
labelFlash.pack()
MSG="Hello World"
str_list=[]
for i in range(len(MSG)):
    str_list.append(MSG[:i+1])
words=str_list


indx=0
def update():
    global indx
    if indx>=len(words):
        indx=0
    w.set(words[indx])
    labelFlash.config(text=words[indx])
    indx+=1
    root.after(500, update)#500 ms


update()
root.mainloop()