It is documented to be, and the LanguageChange event is caught and processed.
However, retranslateStrings() uses QProgressDialog::setCancelButtonText(),
which unconditionally sets useDefaultCancelText=true, blocking any further
changes to the button text by subsequent LanguageChange events.
The fix is to use extracted QProgressDialogPrivate::setCancelButtonText()
which - quite intentionally - doesn't set useDefaultCancelText.
Task-number: QTBUG-40504
Change-Id: I6e701deda10c454cb088c0b0778ac2d6adff574a
Reviewed-by: David Faure <david.faure@kdab.com>