tkinter frame not expanding to fit window?

[Peter Otten]

Zobeid Zuma wrote:

> I've just started working through the tutorial here → http://
> www.tkdocs.com/tutorial/firstexample.html and I already hit some behavior
> that I don't understand. The frame doesn't expand when I resize the
> window! The tutorial says these lines should do it:
> 
> mainframe.columnconfigure(0, weight=1)
> mainframe.rowconfigure(0, weight=1)
> 
> As an experiment I tried commenting those lines out, just to see if
> anything would change, and nothing did. So it seems they aren't working
> for me, but I don't know why. Any suggestions?
> 
> This is all running on Ubuntu MATE 17.10 and tk8.6.

Here is a minimalistic example with a red Frame in a blue window:

import tkinter as tk

root = tk.Tk()
root["background"] = "blue"

frame = tk.Frame(root, background="red")
frame.grid(row=0, column=0, sticky=tk.NSEW)

root.rowconfigure(0, weight=1)
root.columnconfigure(0, weight=1)

root.mainloop()

When you run it as is you should see the red frame.
When you remove the lines

root.rowconfigure(0, weight=1)
root.columnconfigure(0, weight=1)

you should see the blue window instead. When you put those lines back in, 
but change the line

frame.grid(row=0, column=0, sticky=tk.NSEW)

to

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

you will also see blue. 

So my crystal ball says that in the code that you don't show you forgot to 
make the Frame "sticky".