I've created an example here, where you can test the strange behaviour in Chrome/Chromium:
http://zkfiddle.org/sample/3srolnm/1-Update-window-title-onBlur

In Firefox it works like a charm, when you modify Name field and move out with tab, window title is updated and constraint for mail element is not checked yet.

However, in Chrome when you modify the name, window title is updated and constraint is checked.