customtkinter

Coding guidelines for CustomTkinter, a Python library for building desktop interfaces. They cover application structure, visual themes, reusable UI components, and common mistakes.

In plain words
What is it for?
Structuring CustomTkinter apps with classes, setting appearance and colour themes, organising components, and checking code for performance and maintainability problems.
Why use it?
They help keep interface code organised and easier to maintain as the application grows, while avoiding inconsistent themes and mixed-up UI logic.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/sanjeed5/awesome-cursor-rules-mdc/customtkinter
Clone the repo
git clone --depth 1 https://github.com/sanjeed5/awesome-cursor-rules-mdc
Per session 290 This file is loaded in full into every session.
When invoked 290 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00290 $0.00290
Opus 5 $0.00145 $0.00145
Sonnet 5 $0.00058 $0.00058
Haiku 4.5 $0.00029 $0.00029

Measured 3d ago against content hash ea8bc55ec5b7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

customtkinter scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

rules-mdc/customtkinter.mdc · 38 lines

What it actually says

customtkinter Best Practices

This document outlines the definitive best practices for developing applications with customtkinter. Adhering to these guidelines ensures your UI code is consistent, maintainable, performant, and leverages the full power of the library.

1. Code Organization: Class-Based Applications

Always structure your customtkinter applications using a class that inherits from customtkinter.CTk. This encapsulates UI logic, promotes modularity, and simplifies state management.

❌ BAD: Procedural spaghetti code

import customtkinter as ctk

# Theme setup (often forgotten or inconsistent)
ctk.set_appearance_mode("System")
ctk.set_default_color_theme("blue")

app = ctk.CTk()
app.geometry("400x240")
app.title("My App")

def on_button_click():
    print("Button clicked!")
    # Logic mixed directly here

label = ctk.CTkLabel(app, text="Hello!")
label.pack(pady=10)

button = ctk.CTkButton(app, text="Click Me", command=on_button_click)
button.pack(pady=10)

app.mainloop()

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 38 lines · 0 tokens per session scan A ea8bc55ec5b7

Subscribe to this mod's changes

customtkinter is a cursor rule published in the GitHub repository sanjeed5/awesome-cursor-rules-mdc (3,570 stars, last pushed 3mo ago), licensed CC0-1.0. It adds 290 tokens to every session, about $0.0014 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.