# tk_4x4_ButtonLayout_demo.py

import tkinter as tk

def on_enter(event):
	event.widget.config(bg="red")
	event.widget.config(fg="white")

def on_leave(event):
    widget = event.widget
    if button_colors[widget] == 'green':
        widget.config(bg="green")
        widget.config(fg="white")
    else:
        widget.config(bg="yellow")
        widget.config(fg="gray")

def on_click(event):
    widget = event.widget
    if button_colors[widget] == 'green':
        widget.config(bg="yellow")
        widget.config(fg="gray")
        button_colors[widget] = 'yellow'
    else:
        widget.config(bg="green")
        widget.config(fg="white")
        button_colors[widget] = 'green'

root = tk.Tk()
root.geometry("400x400+10+10")
root.title("# tk_4x4_ButtonLayout_demo.py")

button_colors = {}  # Dictionary to store button colors

for i in range(4):
    root.grid_rowconfigure(i, weight=1)
    root.grid_columnconfigure(i, weight=1)
    for j in range(4):
        button = tk.Button(root, text=f"{i*4+j+1}", font=("Arial", 50), fg="gray", bg="yellow")
        button.grid(row=i, column=j, sticky="nsew")
        button.bind("<Enter>", on_enter)
        button.bind("<Leave>", on_leave)
        button.bind("<Button-1>", on_click)
        button_colors[button] = 'yellow'  # Initial color

root.mainloop()