Lesson 3 · 3 of 20

Buttons and their action · tkinter

A tkinter button with command: every click calls a function that updates a counter. Plus disabled buttons with state.

tkinter · Buttons and their action in DMarlon Studio: the example's code and the window it opens when run

count = 5 stores the number of clicks. It starts at 5 so the label already shows a value when the window opens: text=f"Clicks: {count}".

A button (ttk.Button) has its text and, in `command`, the function to run when it is pressed. You pass the function's name, add, without parentheses: add() would call it just once, while creating the button, and never on a click.

add() adds one and changes the text with `label.config(text=...)`: config (or configure) changes any option of a widget that already exists. global count is needed because the function changes a variable defined outside it. reset() sets it back to zero.

The two buttons live inside a ttk.Frame and are placed with pack(side="left"), side by side (frames and pack get their own lessons later). The last one has `state="disabled"`: it is greyed out and does not respond.

In DMarlon Studio this is the Button in the palette. In the inspector you assign its *On press* event, and the studio writes the method that command points to; you only fill in what it does.

Code · main.py

import tkinter as tkfrom tkinter import ttkroot = tk.Tk()root.title("Click counter")root.geometry("400x250")count = 5  # starts at 5, so the label already shows a numberlabel = ttk.Label(root, text=f"Clicks: {count}", font=("Helvetica", 24))label.pack(pady=(34, 20))def add():    global count    count += 1    label.config(text=f"Clicks: {count}")def reset():    global count    count = 0    label.config(text=f"Clicks: {count}")# A frame keeps the two buttons side by side.row = ttk.Frame(root)row.pack()ttk.Button(row, text="Add one", command=add).pack(side="left", padx=6)ttk.Button(row, text="Reset", command=reset).pack(side="left", padx=6)# A disabled button: visible, but it cannot be clicked.ttk.Button(root, text="Not available", state="disabled").pack(pady=18)root.mainloop()

Key points

command takes the function, without parentheses.
config(text=...) changes a widget that already exists.
state="disabled" disables a button; "normal" enables it again.
global lets a function change a variable defined outside it.

Exercise

Add a «Subtract one» button that takes one from the counter without letting it go below zero.