.abc

agfdhafgdfgcbxcvbhgfhsdfbxcgfhfgh

You'd have to write a function to use for adding numbers to the textbox that checks the number's length immediately and disables the button(s) there and then if the length of the number is 4.

Tkinter isn't thread safe so you'd have to have a bit more "fun" to get a solution working with the threading library.

2 Likes