I found this feature so cool I want to post it in both the general forum and the fastmail forum. (
Yes I know better and won't do it. )
When of my biggest pet peeves with email composition is the tiny text area you get to compose your mesage. Its very difficult to compose a large message when you can only view a small amount of it at one time.
The fastmail composition textarea is only 12 rows long. The email discussions composition textarea is only 21 rows. A little better but not good enough.
I have found a firefox extension that allows you to resize the text area. You simply grab the edge of the textarea and drag for a new size.
The extension url is here
http://www.extensionsmirror.nl/index.php?showtopic=2796
The extension is free. I am not affiliated with the author.