from tkinter import *
from tkinter import messagebox

# Create the window
top = Tk()
top.geometry("300x150")


# Event handlers
def do_calculation():
    # TODO handler code goes here
    pass


# TODO Widgets go here
lbl_num1 = Label(top, text="Num 1")
lbl_num1.place(x=5, y=5)

lbl_num2 = Label(top, text="Num 2")
lbl_num2.place(x=5, y=30)

lbl_operation = Label(top, text="Operation")
lbl_operation.place(x=5, y=55)

txt_num1 = Entry(top)
txt_num1.place(x=90, y=5)

txt_num2 = Entry(top)
txt_num2.place(x=90, y=30)

om_operation_text = StringVar()
om_operation_text.set("+")
om_operation = OptionMenu(top, om_operation_text, "+", "-", "*", "/")
om_operation.place(x=90, y=60)

btn_calculate = Button(top, text="Calculate", command=do_calculation)
btn_calculate.place(x=90, y=90)

lbl_result_text = StringVar()
lbl_result = Label(top, textvariable=lbl_result_text, font="Helvetica 18 bold")
lbl_result_text.set("0")
lbl_result.place(x=90, y=120)


# Show the window
top.mainloop()