How to prevent Tkinter window opening before being called?

Question

When I run this script, two windows appear, one for the file selection and the Tkinter window. How can I change this so that the Tkinter window only opens after a file has been

Answer 1

The window master does open only after the file dialog closure (try to change its title to check), the first window you see is the parent window of the file dialog. Indeed, the tkinter file dialogs are toplevel windows, so they cannot exist without a parent window. So the first window you see is the parent window of the file dialog.

The parent window can however be hidden using the withdraw method and then restored with deiconify:

from tkinter import Tk
from tkinter.filedialog import askopenfilename

def main():
    master = Tk()
    master.withdraw()  # hide window
    my_file = askopenfilename(parent=master)
    master.deiconify()  # show window
    master.mainloop()

if __name__ == '__main__':
    main()