import tkinter.ttk as ttk
from tkinter import *

root = Tk()
root.title("Nado GUI")
root.geometry("300x300")

values=[str(i)+"일" for i in range(1, 32)]
combobox = ttk.Combobox(root, height=5, values=values)
combobox.set("카드 결제일")
combobox.pack()

readonly_combobox = ttk.Combobox(root, height=10, values=values, state="readonly")
readonly_combobox.current(0)
readonly_combobox.set("카드 결제일")
readonly_combobox.pack()

def btncmd():
    print(combobox.get())
    print(readonly_combobox.get())

btn = Button(root, text="click", command=btncmd)
btn.pack()


root.mainloop()