I think the behaviour of “return key” = commit change fits in 99% of the case, but there are still other case where it doesn’t (for example, think of a IP address input box, pressing “.” should validate the input box).
In all case, there is a semantically difference between “validation key pressed” and “commit change to label”.
One could use the former to actually modify the label’s text so that a specific format is set (like me, user type “34”, the text must become “34.00” when displayed), and call the second himself.
Anyway, with the setText fix from the other thread, and the modal hack from Component, I could do what I want for my specific use case.
When loosing focus, you actually intended “rollback change to label”, but not “validation key pressed”. (There is no need to go through the format validation again, in the previous example).