How do you check if a widget has a focus in Tkinter?

In Tkinter, you can check if a widget has focus using the focus_get() method. This method returns the widget object that currently has focus, allowing you to compare it with your target widget to determine if it's focused.

Using focus_get() Method

The focus_get() method is called on the root window and returns the currently focused widget object. You can compare this returned object with your widget to check if it has focus ?

import tkinter as tk

# Create main window
root = tk.Tk()
root.geometry("400x300")
root.title("Focus Check Example")

# Create widgets
entry1 = tk.Entry(root, width=20)
entry1.pack(pady=10)

entry2 = tk.Entry(root, width=20)
entry2.pack(pady=10)

result_label = tk.Label(root, text="Click on an entry field", bg="lightgray")
result_label.pack(pady=20)

def check_focus():
    focused_widget = root.focus_get()
    
    if focused_widget == entry1:
        result_label.config(text="Entry 1 has focus", bg="lightgreen")
    elif focused_widget == entry2:
        result_label.config(text="Entry 2 has focus", bg="lightblue")
    else:
        result_label.config(text="No entry field has focus", bg="lightcoral")

# Button to check focus
check_button = tk.Button(root, text="Check Focus", command=check_focus)
check_button.pack(pady=10)

root.mainloop()

Checking Focus with Event Binding

You can also bind focus events to automatically detect when a widget gains or loses focus ?

import tkinter as tk

root = tk.Tk()
root.geometry("400x250")
root.title("Focus Events Example")

status_label = tk.Label(root, text="Status: No widget focused", bg="white", relief="sunken")
status_label.pack(pady=10, fill="x", padx=10)

def on_focus_in(event):
    widget_name = event.widget.winfo_name()
    status_label.config(text=f"Widget '{widget_name}' gained focus", bg="lightgreen")

def on_focus_out(event):
    widget_name = event.widget.winfo_name()
    status_label.config(text=f"Widget '{widget_name}' lost focus", bg="lightcoral")

# Create entry widgets with focus event bindings
entry1 = tk.Entry(root, name="entry1")
entry1.pack(pady=5)
entry1.bind("<FocusIn>", on_focus_in)
entry1.bind("<FocusOut>", on_focus_out)

entry2 = tk.Entry(root, name="entry2")
entry2.pack(pady=5)
entry2.bind("<FocusIn>", on_focus_in)
entry2.bind("<FocusOut>", on_focus_out)

# Button to demonstrate focus change
tk.Button(root, text="Click me to change focus").pack(pady=10)

root.mainloop()

Practical Example with Focus Validation

Here's a practical example that validates input when a field loses focus ?

import tkinter as tk
from tkinter import messagebox

root = tk.Tk()
root.geometry("350x200")
root.title("Focus Validation Example")

def validate_email(event):
    email = email_entry.get()
    if "@" not in email and email:
        messagebox.showwarning("Invalid Email", "Please enter a valid email address")
        email_entry.focus_set()  # Return focus to the field

def check_current_focus():
    focused = root.focus_get()
    if focused:
        widget_type = focused.__class__.__name__
        result_label.config(text=f"Current focus: {widget_type}")
    else:
        result_label.config(text="No widget has focus")

tk.Label(root, text="Email:").pack(pady=5)
email_entry = tk.Entry(root, width=30)
email_entry.pack(pady=5)
email_entry.bind("<FocusOut>", validate_email)

tk.Label(root, text="Password:").pack(pady=5)
password_entry = tk.Entry(root, width=30, show="*")
password_entry.pack(pady=5)

result_label = tk.Label(root, text="Click to check focus", bg="lightgray")
result_label.pack(pady=10)

check_btn = tk.Button(root, text="Check Current Focus", command=check_current_focus)
check_btn.pack(pady=5)

root.mainloop()

Key Methods for Focus Management

Conclusion

Use focus_get() to check which widget currently has focus by comparing the returned object with your target widget. Combine this with focus events like <FocusIn> and <FocusOut> for dynamic focus tracking and validation.