Why not open the child window by creating your own block using your own button:
from tkinter import * def messageWindow(): win = Toplevel() win.title('warning') message = "This will delete stuff" Label(win, text=message).pack() Button(win, text='Delete', command=win.destroy).pack() root = Tk() Button(root, text='Bring up Message', command=messageWindow).pack() root.mainloop()
source share