Hiding a progressbar in tkinter

[MRAB]

On 2019-06-26 16:47, Cecil Westerhof wrote:
> I just started with GUI stuff in tkinter. I have a progressbar, but I
> want it to be only visible when it is used. So I tried the following:
>      window = Tk()
>      window.title(window_str)
>      frame  = Frame(window)
>      frame.pack(side = "top", fill = "both", expand = True)
>      Button(window, text = button_str, command = select_dir).pack()
>      progress = ttk.Progressbar(window, orient = "horizontal", length = 200,
>                                 mode = "determinate")
>      progress.pack()
>      progress.lower(frame)
>      window.mainloop()
> 
> But that does not hide the progressbar. What am I doing wrong?
> 
> I could use pack_forget, but that will change the dimensions of the
> window.
> 
The progress bar isn't hidden because there's nothing on top of it to 
hide it.

import tkinter as tk
import tkinter.ttk as ttk

window = tk.Tk()
window.title(window_str)
frame = tk.Frame(window)
frame.pack(side='top', fill='both', expand=True)
tk.Button(window, text=button_str, command=select_dir).pack()

# Create a frame to hold the progress bar.
progress_frame = tk.Frame(window)
progress_frame.pack(fill='x', expand=True)

# Put the progress bar into the progress frame, ensuring that it fills 
the grid cell.
progress = ttk.Progressbar(progress_frame, orient='horizontal', 
length=200, mode='determinate')
progress.grid(row=0, column=0, sticky='nsew')

# Now put a blank frame into the progress frame over the progress bar, 
ensuring that it fills the same grid cell.
blank = tk.Frame(progress_frame)
blank.grid(row=0, column=0, sticky='nsew')

# Raise the progress bar over the blank frame to reveal it.
progress.tkraise()

# Lower the progress bar underneath the blank frame to hide it.
progress.lower()

window.mainloop()