[Tkinter] Trouble changing Font within tkinter frame title

[menator01]

I did a version of your code. You can look at the way I did the styling and maybe it will help.

#! /usr/bin/env python3

import tkinter as tk
from tkinter import ttk
from ttkbootstrap import Style
import sys

class Window:
    def __init__(self, parent):
        self.parent = parent
        self.parent.rowconfigure(0, weight=1)
        self.parent.columnconfigure(0, weight=1)

        # Create some styles
        exit_btn = Style()
        exit_btn.map('danger.TButton', background = [
        ('disabled', 'tomato'), ('active', 'red')])
        exit_btn.configure('danger.TButton', font=('verdana', 12, 'bold'))

        nb = ttk.Style()
        cur_nb_theme = nb.theme_use()
        nb.theme_settings(cur_nb_theme, {'TNotebook.Tab': {'configure':
                                        {'font': ('comic sans ms', 12, 'bold'),
                                         'foreground': 'blue', 'background': 'lightblue'}
                                        }})


        # Container frame to hold everything
        container = tk.Frame(self.parent)
        container.grid(column=0, row=0, sticky='news')
        container.grid_columnconfigure(0, weight=3)

        # Configure the header
        label = tk.Label(container)
        label['text'] = 'DGRF Frequency Synthesizer 45 MHz - 22 GHz'
        label['font'] = ('comic sans ms', 18, 'bold')
        label['foreground'] = 'steel blue'
        label['relief'] = 'groove'
        label['pady'] = 3
        label.grid(column=0, row=0, sticky='new')

        # Create the notebook
        notebook = ttk.Notebook(container)
        notebook.grid(column=0, row=1, sticky='new')

        # Create and add the tabs
        tab1 = ttk.Frame(notebook)
        tab1.grid(column=0, row=0, sticky='new')

        tab2 = ttk.Frame(notebook)
        tab2.grid(column=1, row=0, sticky='new')

        notebook.add(tab1, text='Reference Chain')
        notebook.add(tab2, text='CW Output')

        # Create a container frame for the two info frames and button
        btm_container = tk.Frame(container)
        btm_container.grid(column=0, row=2, sticky='new', pady=3)
        btm_container.grid_columnconfigure(0, weight=1)
        btm_container.grid_columnconfigure(1, weight=3)
        btm_container.grid_columnconfigure(2, weight=1)
        # for i in range(3):
        #     btm_container.grid_columnconfigure(i, weight=3, uniform='btm')

        # Create error message label
        error_label = ttk.Label(btm_container, anchor='w', background='lightblue')
        error_label['text'] = 'Error Messages:'
        error_label['padding'] = [10, 0, 0, 0]
        error_label['font'] = ('tahoma', 10, 'bold')
        error_label['foreground'] = 'navy'
        error_label.grid(column=0, row=0, sticky='news')

        # Create message label
        message = ttk.Label(btm_container, anchor='w', background='lightblue')
        message['text'] = 'Please Initialize'
        message['font'] = ('tahoma', 10, 'italic bold')
        message.grid(column=1, row=0, sticky='news')

        btn = ttk.Button(btm_container, text='Exit', cursor='hand2')
        btn['command'] = self.exit
        btn['style'] = 'danger.TButton'
        btn.grid(column=2, row=0, sticky='new', padx=2)

        # Create some data for the tabs
        for i in range(20):
            label = tk.Label(tab1, text=f'Line {i} text for tab1')
            label.grid(column=0, row=i, sticky='news')

        for i in range(20):
            label = tk.Label(tab2, text=f'Line {i} text for tab2')
            label.grid(column=0, row=i, sticky='news')

    # Create the method/function for the exit button
    def exit(self):
        sys.exit()

def main():
    root = tk.Tk()
    # root.geometry('800x600+250+250')
    # root.resizable(0, 0)
    root['padx'] = 5
    root['pady'] = 3
    root.title('Part Number: DGRF2820 Rev1      Software ver 1.0')
    Window(root)
    root.mainloop()

if __name__ == '__main__':
    main()

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