import tkinter
import contextlib

class TextIO:
    def __init__(self, text):
        self.text = text
    def write(self, msg):
        self.text.insert(tkinter.END, msg)
    def flush(self):
        pass

def button_pressed():
    print("The button was pressed.")

root = tkinter.Tk()
text = tkinter.Text(root)
text.pack()

button = tkinter.Button(root, text="click me",  command=button_pressed)
button.pack()

with contextlib.redirect_stdout(TextIO(text)):
    root.mainloop()