User blog comment:Rappy 4187/Technical Update: June 18, 2013/@comment-1192804-20130618161855

"With the visual editor disabled, re-selecting a message wall or forum text area will extend its height by roughly 20px each time you repeat the process."

I don't think it's limited to just message walls and forums. Whenever I edit any article with the visual editor disabled, it automatically always adds an extra space to the very bottom. Just editing an article and clicking Preview > Show Changes shows it. It's really frustrating me and I hope it gets fixed soon.