Python tkinter multiple commands for one button

The simplest solution is to put the questions in a list, and use a global variable to track the index of the current question. The "next question" button needs to simply increment the index and then show the next question.

Using classes would be better than global variables, but to keep the example short I won't use classes.

Example:

import Tkinter as tk

current_question = 0
questions = [
    "Shall we play a game?",
    "What's in the box?",
    "What is the airspeed velocity of an unladen swallow?",
    "Who is Keyser Soze?",
]

def next_question():
    show_question(current_question+1)

def show_question(index):
    global current_question
    if index >= len(questions):
        # no more questions; restart at zero
        current_question = 0
    else:
        current_question = index

    # update the label with the new question.
    question.configure(text=questions[current_question])

root = tk.Tk()
button = tk.Button(root, text="Next question", command=next_question)
question = tk.Label(root, text="", width=50)

button.pack(side="bottom")
question.pack(side="top", fill="both", expand=True)

show_question(0)

root.mainloop()