Saving GUI entries to a text file

This is the first time I've used tkinter and GUI in Python, so I'm pretty much a novice.

I have a big GUI form that I made with tkinter. It uses all the classic tkinter widgets: text entry boxes, spinboxes, option menus, radio buttons, and check buttons. What I want to do is let a user enter data into the GUI form and then press the Save button to save everything to a text file. Unfortunately, I can't find many examples of saving data like this to a text file. Here is a generic sample of my code.

import tkinter as tk
from tkinter import ttk

variables = dict()

root = tk.Tk()
root.title('Generic Form')
root.columnconfigure(0, weight=1)

ttk.Label(root, text='Generic Form', font=("TkDefaultFont", 16)).grid()

drf = ttk.Frame(root)
drf.grid(padx=10, sticky=(tk.N + tk.S))
drf.columnconfigure(0, weight=1)

g_info = ttk.LabelFrame(drf, text='Generic Data')
g_info.grid(row=0, column=0, sticky=(tk.W + tk.E))

variables['Scenario ID'] = tk.StringVar()
ttk.Label(g_info, text='Scenario ID').grid(row=0, column=0)
ttk.Entry(g_info, textvariable=variables['Scenario ID']).grid(row=1, column=0, sticky=(tk.W + tk.E))

variables['Integer Value'] = tk.IntVar()
ttk.Label(g_info, text='Integer Value').grid(row=2, column=0)
ttk.Spinbox(g_info, textvariable=variables['Integer Value'], from_=0, to=100, increment = 1).grid(row=3, column=0, sticky=(tk.W + tk.E))

variables['OPTIONS'] = tk.StringVar()
option_var = tk.StringVar(value='Choose')
choices = ('This', 'That', 'The Other Thing')
ttk.Label(g_info, text='OPTIONS').grid(row=4, column=0, sticky=(tk.W + tk.E))
ttk.OptionMenu(g_info, option_var, *choices).grid(row=5, column=0, sticky=(tk.W + tk.E))

choice_default = tk.StringVar(value=F)
variables['CHOICE'] = tk.StringVar()
choice_frame = ttk.Frame(g_info)
ttk.Label(g_info, text='CHOICE').grid(row=6, column=0, sticky=(tk.W + tk.E))
choice_frame.grid(row=7, column=0, sticky=(tk.W + tk.E))
for choice in ('T', 'F'):
    ttk.Radiobutton(choice_frame, value=choice, test=choice, variable=choice_default.pack()

buttons = tk.Frame(drf)
buttons.grid(column=1, pady=20, sticky=(tk.W + tk.E))
save_button = ttk.Button(buttons, test='Save')
save_button.pack(side=tk.RIGHT)

def on_save():
   filename = f'C:/test.txt'
   data = dict()
   with open(filename, 'w', newline='' as fh:
      fh.write("\n")

save_button.configure(command=on_save)
root.mainloop()

Here is the output text I'm trying to get.

Generic Data
  Scenario ID = Scenario 1
  Integer Value = 51
  Options = The Other Thing
  Choice = T

Most of what I know with tkinter is from the book Python GUI Programming with Tkinter by Alan D. Moore. Unfortuantely, this book only describes how to save data into a CSV file. For the project I'm working on, I need it saved in a text file. I know there's a way to do this, but I can't find any examples except for the Entry widget.

After some trial and error, I have finally found a solution:

import tkinter as tk
from tkinter import ttk

variables = dict()

root = tk.Tk()
root.title('Generic Form')
root.columnconfigure(0, weight=1)

ttk.Label(root, text='Generic Form', font=("TkDefaultFont", 16)).grid()

drf = ttk.Frame(root)
drf.grid(padx=10, sticky=(tk.N + tk.S))
drf.columnconfigure(0, weight=1)

frame_info = ttk.LabelFrame(drf, text='Generic Data')
frame_info.grid(row=0, column=0, sticky=(tk.W + tk.E))

variables['Scenario ID'] = tk.StringVar()
ttk.Label(frame_info, text='Scenario ID').grid(row=0, column=0)
ttk.Entry(frame_info, textvariable=variables['Scenario ID']).grid(row=1, column=0, sticky=(tk.W + tk.E))

variables['Integer Value'] = tk.IntVar()
ttk.Label(frame_info, text='Integer Value').grid(row=2, column=0)
ttk.Spinbox(frame_info, textvariable=variables['Integer Value'], from_=0, to=100, increment = 1).grid(row=3, column=0, sticky=(tk.W + tk.E))

variables['OPTIONS'] = tk.StringVar()
option_var = tk.StringVar(value='Choose')
choices = ('Choose', 'This', 'That', 'The Other Thing')
ttk.Label(frame_info, text='OPTIONS').grid(row=4, column=0, sticky=(tk.W + tk.E))
ttk.OptionMenu(g_info, variables['OPTIONS'], *choices).grid(row=5, column=0, sticky=(tk.W + tk.E))

choice_default = tk.StringVar(value='F')
variables['CHOICE'] = tk.StringVar()
choice_frame = ttk.Frame(frame_info)
ttk.Label(frame_info, text='CHOICE').grid(row=6, column=0, sticky=(tk.W + tk.E))
choice_frame.grid(row=7, column=0, sticky=(tk.W + tk.E))
for choice in ('T', 'F'):
    ttk.Radiobutton(choice_frame, value=choice, variable=variables['CHOICE']).pack()

def on_save():
    
    
    inc = variables['Scenario ID'].get()
    number = variables['Integer Value'].get()
    menu = variables['OPTIONS'].get()
    boolean = variables['CHOICE'].get()
    
    with open('GUI.txt', 'w') as x:
        x.write( 'Generic Data' ), x.write('\n')
        x.write( f'  Scenario ID = {inc}' ), x.write('\n')
        x.write( f'  Integer Value = {number}' ), x.write('\n')
        x.write( f'  Options = {menu}' ), x.write('\n')
        x.write( f'  Choice = {boolean}' ), x.write('\n')

tk.Button(frame_info, text='Save', command=on_save).grid(row=8, column=0, sticky=(tk.W + tk.E))

root.mainloop()