# example_006.py
from tkinter.filedialog import askopenfilename

def main():
    filename = askopenfilename(title='Markdown öffnen',
                               filetypes=[('Markdown', '*.md'),
                                          ('Compressed Markdown', '*.md.zip')],
                               initialdir='.')
    print(filename)

if __name__ == '__main__':
    main()