First off thanks for the suggestion, however I'm going to shut this one down as it continually gets bumped and we don't plan to implement it at this time.
1) If you really have this issue there is a browser add-on that will help you with this. It will help you with all your browsing and not only d2jsp like this:
https://addons.mozilla.org/en-US/firefox/addon/caps-lock-notifier/2) This a browser level feature, we don't plan to hack that (there is no perfect solution to it with js code).
3) If you are still having this issue after 3 years maybe it's time to get a new keyboard. I know mine makes it extremely easy to tell the caps lock is on