# cycle_entry_focus.py

# cycle_entry_focus.py

from Tkinter import *

master = Tk()
Label(master, text="1st: ").grid(row=0)
Label(master, text="2nd: ").grid(row=1)
Label(master, text="3rd: ").grid(row=2)
Label(master, text="4th: ").grid(row=3)

e1 = Entry(master)
e2 = Entry(master)
e3 = Entry(master)
e4 = Entry(master)

e1.grid(row=0, column=1)
e2.grid(row=1, column=1)
e3.grid(row=2, column=1)
e4.grid(row=3, column=1)

def go_to_next_entry(event, entry_list, this_index):
    next_index = (this_index + 1) % len(entry_list)
    entry_list[next_index].focus_set()

entries = [child for child in master.winfo_children() if isinstance(child, Entry)]
for idx, entry in enumerate(entries):
    entry.bind('<Return>', lambda e, idx=idx: go_to_next_entry(e, entries, idx))

mainloop()