Simple python pop up window

import tkinter
def popupmsg(msg):
    popup = tkinter.Tk()
    popup.wm_title("!")
    label = tkinter.Label(popup, text=msg,justify='left')
    label.pack(side="top", fill="x", pady=10)
    B1 = tkinter.Button(popup, text="Okay", command = popup.destroy)
    B1.pack()
    popup.mainloop()

Lost track of the author, but this is the simplest window I have seen in python. I used it to make a simple inline help message for the debugger. It is actually done, version 1.0 anyway.