Setting the AJAX refresh rate to zero does not stop requests

On the block configuration page, it states Setting this number to zero will disable ajax refresh, and the inbox will only updated if/when the page is refreshed.

Unfortunately this setting does not take effect, but rather hammers the request out as fast as it can.

I will try and put a patch together if I can find some time, but thought I'd raise this issue first.

In order to test:
1. install the module
2. place the "Private Message Notification" block
3. set the Ajax refresh rate to 0
4. view a page with this block on it and check in the browser's inspector at the Network tab