tkinter mainloop

[ast]

Hello

mainloop() is a window method which starts the event manager 
which tracks for events (mouse, keyboard ...) to be send to the 
window.

But if I forget the root.mainloop() in my program, it works well 
anyway, I cant see any failure. Why ?

Second question, is it possible to cancel a mainloop() ?

I neeed this feature because I have a main window "root = Tk()"
which opens a Toplevel secondary window "top = Toplevel()"
and I would like root window to be frozen while the user fills
the top window. 

thx