Tkinter: is there a has_focus method or property for a window?

[Harlin Seritt]

I have two windows. One is a main config window. The other is an 'Add
Setting' window. Both are using two different classes.

Once the Add Setting button is clicked on the Add Setting window, the
setting is written to file. At that time the main config window should
update its setting listing but it doesn't because it doesn't know it
should.

I do notice that when the Add Setting window closes, the focus goes
right back to the main config window. Is there a "has focus" event that
can trigger a command for this window?

Also, if there is another way to get this done, I am open to
suggestions.

Thanks,

Harlin Seritt