[New-bugs-announce] [issue44548] ttk Indeterminate Progressbar Not Animating Correctly After `start`

[Phil Soucheray]

New submission from Phil Soucheray <souch32 at me.com>:

After running `start` on an indeterminate Progressbar, it animates to one side, goes back to the other and then right before it reaches the end it disappears. I've attached a sample script below and a screen recording. This is running on macOS 11.3 and python 3.9.6 with the tkinter version that is packaged with the 3.9.6 installer. 


```
from tkinter import *
from tkinter.ttk import *
import time

window = Tk()
window.title('Test')
window.geometry('400x250+1000+300')


pb = Progressbar(window, orient=HORIZONTAL, length=100, mode='indeterminate')
pb.pack(expand=True)

Button(window, text='Start', command=pb.start).pack()

window.mainloop()
```

----------
components: Tkinter
files: Screen Recording 2021-07-01 at 1.11.26 PM.mov
messages: 396828
nosy: souch3
priority: normal
severity: normal
status: open
title: ttk Indeterminate Progressbar Not Animating Correctly After `start`
type: behavior
versions: Python 3.9
Added file: https://bugs.python.org/file50137/Screen Recording 2021-07-01 at 1.11.26 PM.mov

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue44548>
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