import sys from Tkinter import * makemodal = (len(sys.argv) > 1) def dialog(): win = Toplevel() Label(win, text='information').pack() Button(win, text='OK', command=win.destroy).pack() if makemodal: win.focus_set() win.grab_set() win.wait_window() print 'dialog exit' root = Tk() Button(root, text='popup', command=dialog).pack() root.mainloop()