import os
import tkinter
from tkinter import scrolledtext

main_window = tkinter.Tk()
main_window.geometry('1280x720')
main_window.title('Text Editor 3000')

def open_file(filename):
    pass

files = os.listdir('.')
for i in range(len(files)):
    filename = files[i]
    btn = tkinter.Button(main_window, text=filename,
                         font=('Consolas', 14),
                         command=lambda: open_file(filename))
    btn.grid(column=0, row=i)

def create_new(file):
    pass

def save_file():
    pass

new_btn = tkinter.Button(main_window, text='Create new file',
                         font=('Consolas', 14), command=create_new)
new_btn.grid(column=1, row=0)

new_btn = tkinter.Button(main_window, text='Save file',
                         font=('Consolas', 14), command=save_file)
new_btn.grid(column=2, row=0)

filename = tkinter.Entry(main_window, width=20)
filename.grid(column=3, row=0)

txt = scrolledtext.ScrolledText(main_window, width=100, height=30)
txt.grid(column=1, row=1, columnspan=10, rowspan=10)

main_window.mainloop()