Twitter is always testing something with users; this week, they have a couple visual experiments underway. Another new feature, which Mashable first noticed in a tweet sent by Twitter's head of communications, Carolyn Penner, allows users more space to comment when they are retweeting another user. "Retweet with Comment" surfaces the retweeted message as an image, leaving users with just under 140-characters to share their own thoughts. Previously, if someone wanted to add their own commentary to a retweet, they could click "Quote Tweet" to do so. This limited user comments by forcing them to fit both the original tweet and the added material into the 140-character limit. Another feature, noticed on Thursday by some users, positions tweet images above the tweet's text instead of below it.