Emoticons aren't always transformed into graphics
This is a bug that has existed for quite a long time (I think maybe a month or longer) but I haven't had time to report it.
The problem is that emoticons defined in an appropriate file sometimes are transformed to graphics and sometimes not. I attach 2 examples - in each of them there exist an emoticon (once ";)", once ":D") that - in the same chat - once is transformed and once not. It happens in nearly all my chats.