How to create window independent each other?

Question

I want to create independent window. each create window, when caller window close or destroy. so far is create window without problem. but console warning message that i dont know what is this.

Console warning

can't invoke "event" command: application has been destroyed while executing "event generate $w <>" (procedure "ttk::ThemeChanged" line 6) invoked from within "ttk::ThemeChanged"

import tkinter

class MainWindow(tkinter.Tk):
    def __init__(self, condition):
        super().__init__()

        self.title("Main Window ")
        self.geometry("640x360")

        if (condition == 1):
            DashboardWindow() 
            self.destroy()
            

class DashboardWindow(tkinter.Tk):
    def __init__(self):
        super().__init__()

        self.title("Dashboard Window")
        self.geometry("940x560")

    
    
MainWindow(1).mainloop()

Answer 1

It's usually best to avoid having more than on instance of Tk in your application for the reasons stated in the link in the comment I posted under your question.

So below is code showing one way to do that based on what's in your question. In it the DashboardWindow class is derived from tkinter's Toplevel widget. Note that the MainWindow instance is only hidden so isn't destroyed, which means it could be made visible again (via a root.state('normal') call if desired). To demonstrate that I added a Button to the DashboardWindow class.

import tkinter as tk


class MainWindow(tk.Tk):
    def __init__(self, condition):
        super().__init__()

        self.title("Main Window ")
        self.geometry("640x360")

        if condition == 1:
            new = DashboardWindow(self)
            self.wait_visibility(new)  # Wait until it's visible.
            self.withdraw()  # Hide MainWindow


class DashboardWindow(tk.Toplevel):
    def __init__(self, parent):
        super().__init__(parent)

        self.title("Dashboard Window")
        self.geometry("940x560")

        tk.Button(self, text='Main window', command=lambda: parent.state('normal')).pack()


if __name__ == '__main__':

    root = MainWindow(1)
    root.mainloop()

Answer 2

Right now you create a tk.Tk window, then call .destory() on it and then call .mainloop() on it. The .destroy() will destroy the window so you can no longer call any normal tkinter methods on it like .mainloop()

This is your code fixed:

import tkinter


class MainWindow(tkinter.Tk):
    def __init__(self, condition):
        super().__init__()

        self.title("Main Window ")
        self.geometry("640x360")

        if (condition == 1):
            new_window = DashboardWindow()
            self.destroy()
            # We will call .mainloop() here:
            new_window.mainloop()


class DashboardWindow(tkinter.Tk):
    def __init__(self):
        super().__init__()

        self.title("Dashboard Window")
        self.geometry("940x560")


# After this is done, the window will no longer be allive so we can't call `.mainloop()`
MainWindow(1)

I think that your design is flawed. You can have multiple tk.Tk windows (so the windows are independent of each other) but you have to pass in master=... when creating PhotoImages/StringVars/IntVars/... And it doesn't matter how many tk.Tk windows you have, don't call any methods on widgets/windows that have been destroyed.