为什么ttk.Button而不是tk.Toplevel出现在主窗口中？

Question

I have a main UI which gets instantiated like this:

class MyApp(ttk.Frame):
    def __init__(self, master):
        ttk.Frame.__init__(self, master)
        (...)

    def make_gui(self):
        (...)
        self.helpButt = ttk.Button(self.InnerRightFrm2, padding=(0, 0),
                                   text='Help', image=help_icon
                                   compound='left', command=self.show_help)
        (...)

def main():
    root = tk.Tk()
    root.title('Myapp')
    root.columnconfigure(0, weight=1)
    root.rowconfigure(0, weight=1)
    root.resizable(True, True)
    root.update()
    gui = MyApp(root)
    gui.mainloop()

When a user clicks Show help button located on the main interface a new Toplevel window should appear. The Toplevel of this window contains two frames: topFrame0 on row=0 and topFrame1 on row=1 . I create a third frame inside topFrame1 to put "Close" Button in in. Here is how I do it:

def show_help():
    top_win = tk.Toplevel()
    top_win.title('Help')
    top_win.resizable(0, 0)

    topFrame0 = ttk.Frame(top_win, borderwidth=2, relief='groove')
    topFrame0.grid(row=0, column=0, sticky='nsew')
    topFrame1 = ttk.Frame(top_win, borderwidth=2, relief='flat')
    topFrame1.grid(row=1, column=0, sticky='nsew')
    buttonFrame = ttk.Frame(topFrame1, borderwidth=2, relief='groove').grid()
    ttk.Button(buttonFrame, padding=(0, 2), text='Close', command=top_win.destroy).grid(sticky='e')

However, instead of appearing in the right botton of Toplevel window (notice red arrow in the screenshot), "Close" Button appears in the right bottom of the main MyApp window! How can this even happen?

Answer 1

In line

buttonFrame = ttk.Frame(...).grid()

you assign None to buttonFrame because grid() returns None so you have later ttk.Button(None, ...) and you add button to main window.

You need

buttonFrame = ttk.Frame(...)
buttonFrame.grid()