Apparently request.getParameter(Constants.CANCEL_PROPERTY) doesn't work when
posting mulipart/form-data so using <html:cancel/> to submit a form is ignored.
This means that the form.validate() function isn't skipped on the form.
Presumably Action.isCancelled() won't work either unless the fix puts the
CANCEL_PROPERTY in the request before the form is passed to the action.
This has been posted to the newsgroups before and someone was going to fix it
but it doesn't appear to work yet, hence the bug report.
The docs for html:cancel and html:file don't mention any limitations along