Highlight first 140 characters

When posting to a StatusNet site that allows for statuses greater than 140 characters, it would be nice to know when I've passed 140 characters. This is both for curiosity's sake, and practically, since my posts are also reflected on a certain non-OStatus site that doesn't allow for dynamic sizing of statuses (in fact, keeping in mind the auto-URLification of the rest of the post would be nice, too).

Anyway, it'd be great if this was easier to see. Two ways to implement:

* Keep a running count of characters as well as a count of characters remaining.
* Color the portion of the message that is greater than 140 characters.

Currently, I allow for 1024 character micoblogs on status.planb-security.net, so I just need to keep in my head that the magic number is 884 (1024-140). The downside to this is Math is Hard.