Tkinter - 当我有不同类型的类时，如何正确使用“ttk.style()”语句？

Question

In my real code I have a main window where the user can choose to open other kind of windows. In the main one, I defined the ttk style using the ttk.style() statement. It works, but if I define the same style in the other classes dedicated for the other windows, the ttk.style() doesn't work anymore. Why? Below is an example:

from tkinter import *
from tkinter import ttk

class MainWindow:
    def __init__(self):

        self.parent=Tk()
        self.parent.geometry("400x400")
        self.parent.title(self.main_name)
        self.parent.configure(background="#f0f0f0")

        style=ttk.Style()
        style.configure("TButton", background="red", padding=0)

        MyButton=ttk.Button(self.parent, text="open a new window", command=self.Open)
        MyButton.pack()

        self.parent.mainloop()

    def Open(self):
        obj=NewWindow()

class NewWindow():
    def __init__(self):

        self.parent=Tk()
        self.parent.geometry("400x400")
        self.parent.configure(background="#f0f0f0")

        style=ttk.Style()
        style.configure("TButton", background="red", padding=0)
    
        MyButton=ttk.Button(self.parent, text="This button has not a custom style.. why?")
        MyButton.pack()

if __name__=="__main__":
    app=MainWindow()

Why the window from the NewWindow class doesn't use the custom ttk style like the other one from the MainWindow class?

Then I want to write just one time the ttk instructions, because in my real code, all classes use the same style. What is the best way to do it?

Below is a screenshot about my example:

Answer 1

Every instance of Tk is a separate environment, and cannot share data with other instances of Tk . If you want multiple windows to be able to share information with the first window, you must create instances of Toplevel rather than Tk .

The reason your second window doesn't accept the new styling is that the Style object you created belongs to the original root window. If you want it to affect the new root window you must explicitly tell it so by specifying the master attribute.

style=ttk.Style(master=self.parent)