Moving a window on the screen

[Peter Otten]

ast wrote:

> Why the following program doesn't work ?
> 
> for x in range(0, 100, 10):
>     fen.geometry("200x200+%d+10"   %   x)
>     time.sleep(0.5)
> 
> 
> where fen is a window (fen = Tk())
> 
> The fen window goes from it's initial location to the last one
> but we dont see all the intermediate steps

As Chris says, using sleep() with a gui program usually doesn't work. While 
the script is sleeping the event loop doesn't run and consequently the user 
will not see any updates of the program's state.

Instead of sleeping you have to schedule events that trigger a callback and 
then go back to the event loop. Such a callback may schedule another 
invocation of itself, thus giving you the desired effect:

import tkinter as tk

root = tk.Tk()
xpositions = iter(range(0, 100, 10))

def move_next():
    try:
        x = next(xpositions)
    except StopIteration:
        pass
    else:
        root.geometry("200x200+%d+10" %  x)
        root.after(500, move_next) # have tkinter call move_next again
                                   # in about 500 milliseconds

root.after_idle(move_next)
root.mainloop()