Add Dark Mode to Tkinter GUI – Python Theme Toggle Example

 

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🌙 Bonus Part 1: Adding Dark Mode to Your Tkinter App

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📘 Overview

Dark Mode is more than a visual trend — it's easier on the eyes, especially in low-light environments. In this bonus part, you'll learn how to:

• Create a toggle for light/dark themes

• Dynamically change widget colors

• Implement a reusable dark mode for your Tkinter apps

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🎨 Why Add Dark Mode?

✅ Benefits:

• Reduces eye strain

• Preferred by many users

• Makes your app look modern and polished

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🧱 Approach

Tkinter doesn’t have built-in themes like “dark” or “light,” so we define two color palettes and apply them dynamically to your widgets.

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✅ Step-by-Step: Dark Mode Toggle Example

import tkinter as tk

# Color themes
LIGHT_THEME = {
    "bg": "#ffffff",
    "fg": "#000000",
    "button_bg": "#f0f0f0",
    "entry_bg": "#ffffff"
}

DARK_THEME = {
    "bg": "#2e2e2e",
    "fg": "#ffffff",
    "button_bg": "#3e3e3e",
    "entry_bg": "#4e4e4e"
}

class DarkModeApp(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("Dark Mode Toggle")
        self.geometry("300x200")
        self.theme = LIGHT_THEME

        self.label = tk.Label(self, text="Hello, Tkinter!", font=("Arial", 14))
        self.label.pack(pady=10)

        self.entry = tk.Entry(self)
        self.entry.pack(pady=5)

        self.toggle_btn = tk.Button(self, text="Toggle Dark Mode", command=self.toggle_theme)
        self.toggle_btn.pack(pady=10)

        self.apply_theme()

    def apply_theme(self):
        self.configure(bg=self.theme["bg"])
        self.label.configure(bg=self.theme["bg"], fg=self.theme["fg"])
        self.entry.configure(bg=self.theme["entry_bg"], fg=self.theme["fg"], insertbackground=self.theme["fg"])
        self.toggle_btn.configure(bg=self.theme["button_bg"], fg=self.theme["fg"])

    def toggle_theme(self):
        self.theme = DARK_THEME if self.theme == LIGHT_THEME else LIGHT_THEME
        self.apply_theme()

if __name__ == "__main__":
    app = DarkModeApp()
    app.mainloop()

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🧠 Key Concepts

• You store the theme values in dictionaries

• When the user clicks “Toggle Dark Mode”, the theme switches and apply_theme() re-colors everything

• You can expand this to theme more widgets (buttons, frames, checkbuttons, etc.)

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🔌 Bonus: Remember Theme Preference

To store the user’s theme preference:

• Use a simple settings.txt file

• Save dark or light

• Load it when the app starts

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💡 Recap

In this part, you’ve learned:

• How to define and switch between light/dark themes

• How to dynamically apply colors to widgets

• How to build a theme-aware GUI with clean logic

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 next : remember theme preference 

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