如何让Tkinter MessageBox弹窗居中于根窗口而非屏幕

在类结构的Tkinter程序中，让messagebox弹窗居中根窗口的关键是给弹窗方法传入parent=self参数——因为你的App类继承自tk.Tk，self就是根窗口实例，弹窗会以此为基准居中显示。

你只需要修改两处messagebox调用的代码：

1. 在button_submit方法中：

messagebox.showinfo(title='Information', message='Success', parent=self)

2. 在add_to_file方法的异常处理中：

messagebox.showerror('Error', 'Log File Permission Denied!', parent=self)

修改后的完整代码如下：

import tkinter as tk
from tkinter import ttk
from tkinter import messagebox
from datetime import date
from openpyxl import load_workbook


class App(tk.Tk):
    def __init__(self):
        super().__init__()

        # Configure the root window
        self.title('Profit Tool')
        self.geometry('300x220')

        # Details
        self.label = ttk.Label(self, text='Details:')
        self.label.pack()

        self.details = tk.Entry(self)
        self.details.pack()

        # Profit
        self.label = ttk.Label(self, text='Profit/Loss:')
        self.label.pack()

        self.profit = tk.Entry(self)
        self.profit.pack()

        self.label = ttk.Label(self, text='')
        self.label.pack()

        # Button
        self.button = ttk.Button(self, text='Submit', 
        default='active', padding=5, command=self.button_submit)
        self.button.pack()

    def button_submit(self):
         self.add_to_file()
         self.clear_entries()
         messagebox.showinfo(title='Information', message='Success', parent=self)

    def add_to_file(self):
        # Read Content From File
        try:
            wb = load_workbook(filename="Tool Log.xlsx")
            ws = wb.active

            row = ws.max_row + 1
            get_date = date.today()
            today = get_date.strftime('%d/%m/%y')

            # Format Date Cell
            cell = ws.cell(column=2, row=row)
            cell.number_format = 'dd/mm/yy;@'
            cell.value = today

            # Format Details Cell
            cell = ws.cell(column=5, row=row)
            cell.value = self.details.get()

            # Format Profit Cell
            cell = ws.cell(column=6, row=row)
            cell.number_format = '£#,##0.00'
            cell.value = float(self.profit.get())

            wb.save("Tool Log.xlsx")
            wb.close()

        except PermissionError:
            messagebox.showerror('Error', 'Log File Permission Denied!', parent=self)
            raise Exception('Log File Permission Denied!')

    def clear_entries(self):
        self.details.delete(0, 'end')
        self.profit.delete(0, 'end')


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

内容的提问来源于stack exchange，提问作者Tom Hughes