如何使Tkinter的弹出窗口的position位于主window的中心？

Question

I want to know how one could make the popup window's position relative to the main window. When I tried it the popup window goes and sits at the corner of my computer screen. Here is my code.

def popup_bonus(self):
        win = tk.Toplevel()
        win.wm_title("Error")
        win.configure(bd=0, highlightthickness=0)
        win.overrideredirect(1)
        l = ttk.Label(win, text="Already Exists")
        l.grid(row=0, column=0)

        b = tk.Button(win, text="Okay", command=win.destroy)
        b.grid(row=1, column=0)

Answer 1

First get main window position

    root_x = root.winfo_rootx()
    root_y = root.winfo_rooty()

next add offset to this position

    win_x = root_x + 300
    win_y = root_y + 100

and finally use new position to move toplevel window

    win.geometry(f'+{win_x}+{win_y}')

Doc effbot.org: Basic Widget Methods

---

import tkinter as tk

# --- functions ---

def on_click():
    # get main window position
    root_x = root.winfo_rootx()
    root_y = root.winfo_rooty()

    # add offset
    win_x = root_x + 300
    win_y = root_y + 100

    win = tk.Toplevel()

    # set toplevel in new position
    win.geometry(f'+{win_x}+{win_y}')  

    button = tk.Button(win, text='OK', command=win.destroy)
    button.pack()

# --- main ---

root = tk.Tk()
root.geometry('800x600')           # only size
#root.geometry('+100+200')         # only position
#root.geometry('800x600+100+200')  # both: size and position

button = tk.Button(root, text='OK', command=on_click)
button.pack()

root.mainloop()