This is a known issue: https://github.com/gwtproject/gwt/issues/4468
Solution is to first update to at least 2.7, and use SuperDevMode.
You received this message because you are subscribed to the Google Groups "GWT Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to email@example.com.
To post to this group, send email to firstname.lastname@example.org.
Visit this group at https://groups.google.com/group/google-web-toolkit.
For more options, visit https://groups.google.com/d/optout.