tkinter, pack inside grid and propagation not working

I am trying to create a button with a fixed size. So, I created a Frame (grid) with the size I want and then a child Button (pack) inside of the Frame that takes all the space.

Here is a minimal example:

window = tk.Tk()
frame1 = tk.Frame(window, bg="#ffffff", height=50, width=100)
frame1.grid(row=0, column=0)
frame1.grid_propagate(0)
#frame1.propagate(False)       #  <----- This line makes it work.
button1 = tk.Button(frame1, bg="#000000")
button1.pack(expand=True, fill=tk.BOTH)

Without the commented line above, I expected that it would work (having a rectangle of the specified size), but I get a small square. Why is it not working?

I was not able to find documentation on that .propagate() function. I only found about the grid_propagate() and pack_propagate() functions.

Answer

Right now you have 2 containers: window and frame1. When you use frame1.grid(...), you actually tell the master of frame1, which is window that it should use the grid manager. When you use button1.pack(...), you tell the button’s master (frame1) that it should use the pack manager inside itself.

So when you use frame1.grid_propagate(...), you tell the grid manager (that doesn’t manage the widgets inside frame1), that it should do something, so it ignores you.