How to stop Tkinter Frame from shrinking to fit its contents?

Question

This is the code that's giving me trouble.

f = Frame(root, width=1000, bg="blue")
f.pack(fill=X, expand=True)

l = Label(f, text="hi", width=10, bg="red", fg="white")
l.pack()

If I comment out the lines with the Label, the Frame displays with the right width. However, adding the Label seems to shrink the Frame down to the Label's size. Is there a way to prevent that from happening?

Answer 1

By default, tk frames shrink or grow to fit their contents, which is what you want 99% of the time. The term that describes this feature is "geometry propagation". There is a command to turn geometry propagation on or off when using pack (and a similar one for grid).

Since you are using pack, the syntax would be:

f.pack_propagate(0)

or maybe root.pack_propagate(0), depending on which widget(s) you actually want to affect. However, because you haven't given the frame height, it's default height is 1 pixel so you still may not see the interior widgets. To get the full effect of what you want, you need to give the containing frame both a width and a height.

That being said, the vast majority of the time you should let tkinter compute the size. When you turn geometry propagation off your GUI won't respond well to changes in resolution, changes in fonts, etc. tkinter's geometry managers (pack, place and grid) are remarkably powerful. Learn to take advantage of that power.