import tkinter as tk


class Toolbar(tk.Frame):
    def __init__(self, parent, root, *args, **kwargs):
        super().__init__(parent, *args, **kwargs)
        self.root = root

        self.lbl = tk.Label(self, text='Toolbar')
        self.lbl.pack()


class PageOne(tk.Frame):
    def __init__(self, parent, root, *args, **kwargs):
        super().__init__(parent, *args, **kwargs)
        self.root = root

        self.lbl = tk.Label(self, text='PageOne')
        self.lbl.pack()

        self.btn = tk.Button(self, text='MainPage', command=lambda: self.root.show_frame(MainPage))
        self.btn.pack()


class MainPage(tk.Frame):
    def __init__(self, parent, root, *args, **kwargs):
        super().__init__(parent, *args, **kwargs)
        self.root = root

        self.lbl = tk.Label(self, text='MainPage')
        self.lbl.pack()

        self.btn = tk.Button(self, text='PageOne', command=lambda: self.root.show_frame(PageOne))
        self.btn.pack()


class App(tk.Tk):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._setup_window()
        self.frames = {}

        container = tk.Frame(self, bg='yellow')
        container.pack(side='top', fill='both', expand=True)

        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)
        container.grid_rowconfigure(1, weight=3)

        self.toolbar = Toolbar(container, self, bg='red', height=20)
        self.toolbar.grid(row=0, column=0, sticky='new')

        for page in (MainPage, PageOne):
            frame = page(container, self, bg='blue', height=260)
            self.frames[page] = frame
            frame.grid(row=1, column=0, sticky='nsew')

        self.show_frame(MainPage)

    def _setup_window(self):
        self.geometry('420x280')
        self.title('backup')

    def show_frame(self, page_name):
        frame = self.frames[page_name]
        frame.tkraise()


if __name__ == '__main__':
    app = App()
    app.mainloop()

w.columnconfigure(0, weight=3)
   w.columnconfigure(1, weight=1)