Dynamically fit tkinter window to its content

Question

I have a Toplevel Window with one grid row containing a Label, Entry and a "+" Button (window on startup) When I hit the Add-Button a new row with the same content is generated. But the problem is, that the window doesn't resize and fit to its new contents. Should look like this resized window.

The code is below:

def process_map():
    numbers = {0:'\u2080', 1:'\u2081', 2:'\u2082', 3:'\u2083', 4:'\u2084', 5:'\u2085', 6:'\u2086', 7:'\u2087', 8:'\u2088', 9:'\u2089'}
    button_pos = tk.IntVar(0)
    ENTRIES = {}

    def add_button():
        if button_pos.get() >= 10:
            index = numbers[button_pos.get()//10] + numbers[button_pos.get()%10]
        else:
            index = numbers[button_pos.get()]
        lb = tk.Label(top_root, text='\u03C6'+index)
        lb.grid(row=button_pos.get(), column=0, sticky='NWES')
        entry = tk.Entry(top_root, width=4, relief='sunken', bd=2)
        entry.grid(row=button_pos.get(), column=1, sticky='WE', padx=5, pady=5)
        ENTRIES.update({button_pos.get():entry})
        bt.grid(row=button_pos.get(), column=2, sticky='WE', padx=5, pady=5)
        bt_close.grid(row=button_pos.get()+1, column=1, padx=5, pady=5)
        bt_start.grid(row=button_pos.get()+1, column=0, padx=5, pady=5)
        button_pos.set(button_pos.get()+1)
        center(top_root)

    top_root = tk.Toplevel(root)
    top_root.title('Select \u03C6')
    lb = tk.Label(top_root, text='\u03C6\u2081', height=1)
    lb.grid(row=0, column=0, sticky='NWES')

    entry = tk.Entry(top_root, width=4, relief='sunken', bd=2)
    entry.grid(row=0, column=1, sticky='WE', padx=5, pady=5)
    button_pos.set(button_pos.get()+2)
    ENTRIES.update({button_pos.get():entry})

    bt = tk.Button(top_root, text='+', command=add_button,)
    bt.grid(row=0, column=2, sticky='WE', padx=5, pady=5)

    bt_close = tk.Button(top_root, text='Cancel', width=15, command=top_root.destroy)
    bt_close.grid(row=button_pos.get()+1, column=1, padx=5, pady=5)
    bt_start = tk.Button(top_root, text='Start', width=15)
    bt_start.grid(row=button_pos.get()+1, column=0, padx=5, pady=5)
    center(top_root)
    top_root.mainloop()