Best practice query: Entry field "user's done editing" handling?

[Chris Angelico <rosuav gmail com>]

I have a form with a whole pile of entry fields (GTK2.Entry), and I
need to do some processing (and save the edit) whenever the user's
edited a field and is now done editing. Is there a standard way to
recognize this? I'm thinking of something like the VX-REXX "Verify"
event, which fires on a changed entry field when focus moves to
another control on the same window, but not if focus moves to another
window altogether.

Currently, I'm hooking focus-out-event signals and checking the
current text to see if it differs from a saved copy of the text. I'd
rather not save every time a 'changed' signal comes through, as that
would be hopelessly inefficient most of the time.

What's best practice here?

Chris Angelico