Implementing Dark-mode with on/off function in Simple Python Tkinter program?

Question

I followed this tutorial in creating a very simple text-editor app using Python's Tkinter. What I wanted to do was add the option of using a checkbutton, so when checked, the theme of the text-editor would change to dark-mode theme and when unchecked, would return to the default white theme. How can I do this?

I tried binding a function the checkbutton where it would check the state and depending on the state, change the variables of the frames in the window. For example, if it was:

frame = tk.Frame(colour=white)

as the default, in the function I would put:

frame = tk.Frame(colour=white)

Even to me, this didn't look right. (I know the format is incorrect.)

Here the code (without my attempt at doing the dark-mode):

import tkinter as tk
from tkinter.filedialog import askopenfilename, asksaveasfilename

def open_file():
    """Open a file for editing."""
    filepath = askopenfilename(
        filetypes=[("Text Files", "*.txt"), ("All Files", "*.*")]
    )
    if not filepath:
        return
    txt_edit.delete(1.0, tk.END)
    with open(filepath, "r") as input_file:
        text = input_file.read()
        txt_edit.insert(tk.END, text)
    window.title(f"Simple Text Editor - {filepath}")

def save_file():
    """Save the current file as a new file."""
    filepath = asksaveasfilename(
        defaultextension="txt",
        filetypes=[("Text Files", "*.txt"), ("All Files", "*.*")],
    )
    if not filepath:
        return
    with open(filepath, "w") as output_file:
        text = txt_edit.get(1.0, tk.END)
        output_file.write(text)
    window.title(f"Simple Text Editor - {filepath}")

window = tk.Tk()
window.title("Simple Text Editor")
window.rowconfigure(0, minsize=800, weight=1)
window.columnconfigure(1, minsize=800, weight=1)

txt_edit = tk.Text(window)
fr_buttons = tk.Frame(window, relief=tk.RAISED, bd=2)
btn_open = tk.Button(fr_buttons, text="Open", command=open_file)
btn_save = tk.Button(fr_buttons, text="Save As...", command=save_file)

btn_open.grid(row=0, column=0, sticky="ew", padx=5, pady=5)
btn_save.grid(row=1, column=0, sticky="ew", padx=5)

fr_buttons.grid(row=0, column=0, sticky="ns")
txt_edit.grid(row=0, column=1, sticky="nsew")

window.mainloop()

Answer 1

You Can Do By Installing The Module ttkthemes

pip install ttkthemes

import tkinter as tk
import tkinter.ttk as ttk 
from ttkthemes import ThemedStyle

app = tk.Tk()
app.geometry("200x400")
app.title("Changing Themes")
# Setting Theme
style = ThemedStyle(app)
style.set_theme("scidgrey")

# Button Widgets
Def_Btn = tk.Button(app,text='Default Button')
Def_Btn.pack()
Themed_Btn = ttk.Button(app,text='Themed button')
Themed_Btn.pack()

# Scrollbar Widgets
Def_Scrollbar = tk.Scrollbar(app)
Def_Scrollbar.pack(side='right',fill='y')
Themed_Scrollbar = ttk.Scrollbar(app,orient='horizontal')
Themed_Scrollbar.pack(side='top',fill='x')

# Entry Widgets
Def_Entry = tk.Entry(app)
Def_Entry.pack()
Themed_Entry = ttk.Entry(app)
Themed_Entry.pack()

app.mainloop()