"""
=============================================================
Verify that <Destroy> is run on user window closes, but not 
for still-open windows on a root.quit() (though it _is_ run 
for still-open windows if mainloop() exits without a quit()).

Bind this event on a widget: fires > once if bind on entire
window, because nested widgets are destroyed too

Typical outout, when run in PyEdit's Run Code and close two:
got user close 1
got <destroy> 1
got user close 3
got <destroy> 3
[EOF]

If the root.quit register line is commented-out:
got user close 1
got <destroy> 1
got user close 3
got <destroy> 3
got <destroy> 0
got <destroy> 2
[EOF]
=============================================================
"""

from tkinter import *

root = Tk()
Label(root, text='Root' * 5).pack()

def onDestroy(i): 
    print('got <destroy>', i)

def onClose(i, pop): 
    print('got user close', i)
    pop.destroy()

for i in range(4):
    pop = Toplevel()
    lab = Label(pop, text=str(i) * 10)        # don't bind <destory> to whole window
    lab.pack()
    lab.bind('<Destroy>', lambda e, i=i: onDestroy(i))
    pop.protocol('WM_DELETE_WINDOW', lambda i=i, pop=pop: onClose(i, pop))

root.protocol('WM_DELETE_WINDOW', root.quit)  # <destroy> run iff this line not run 
root.mainloop()