Can't separate verb from noun. In some languages (Lithuanian and maybe in
other) noun form depends on verb and differs from regular noun form.
"mailbox" in accusative case differs from same noun in nominative case.
Leaving only "Expunge" button instead of creating bulky "Expunge mailbox"
button. Issue is not present in 1.5.x. Keeping   in order to separate
button from buttons that work with selected messages