Ok everyone, check out the new dialog for attaching files to emails/posts.
You're going to *love* it. I am *really* happy with how well it came out.
Attaching files no longer requires a "save that's not really a save" of the message, and it doesn't clutter the headers section with a lot of noise. Instead, when you click the "Attach" button, the attachments pane pops up over the message (in all of its CSS3 rounded-corners, gradient-background, drop-shadow Web 2.0-ness) and lets you add as many files as you want, then you can dismiss the window.
TODO: removing attachments does not work yet.
TODO: I want to change the "Attach" button to "Attachments: 0" and have it update dynamically
