Sometimes in web application development the need arises to show a status message or similar notices to a user. This can of course be easily done in some success page but sometimes this page is rendered by a different request because of a redirect. In these cases you can use some query parameters or similar methods but that’s not always easy to use or might even have security problems.
qc.statusmessage tries to solve this problem by giving you a MessageList object which is put into the WSGI environment on ingress and processed on egress to store a list of messages inside a cookie.