This short Python snippet shows you how to read mouse wheel events with the Tkinter GUI toolkit. Windows and Linux have different bindings and read different events, but can be included in the same program code for use with either operating system.

# explore the mouse wheel with the Tkinter GUI toolkit
# Windows and Linux generate different events
# tested with Python25

import Tkinter as tk

def mouse_wheel(event):
    global count
    # respond to Linux or Windows wheel event
    if event.num == 5 or event.delta == -120:
        count -= 1
    if event.num == 4 or event.delta == 120:
        count += 1
    label['text'] = count

count = 0
root = tk.Tk()
root.title('turn mouse wheel')
root['bg'] = 'darkgreen'

# with Windows OS
root.bind("<MouseWheel>", mouse_wheel)
# with Linux OS
root.bind("<Button-4>", mouse_wheel)
root.bind("<Button-5>", mouse_wheel)

label = tk.Label(root, font=('courier', 18, 'bold'), width=10)
label.pack(padx=40, pady=40)

root.mainloop()