"Black" at the end of a Compose Message if you ...

[AkiAki007]

To reproduce.

1. Compose an email with content to the bottom of the pane (and lower)
2. Once your pane is long enough that ir requires scrolling, hit enter severl times to add white space to the bottom
3. Scroll all the way down.
4. Bring your cursor up to the point where there is text, and start hitting the delete button (not backspace)
5. For every line deleted, a black line is added. The back can be removed by simply scrolling back up and down.
Here is an image

[mscott]

I've seen this behavior too. It looks like it's a core Mozilla Composer bug and is not Thunderbird specific. Wanna file it in bugzilla under Editor?

[tve]

sounds like this bug:
http://bugzilla.mozilla.org/show_bug.cgi?id=201435

resolved and fixed :)