One issue is described here, users want to be able to set its size manually and for all (checkbox in Preferences?)
Another issue. If i paste large text in there, it will hide conversation and i wount be able to see incoming messages until i send my message. Getting rid of scrollbars is nice. But sometimes we still need them (yes yes, it’'s IM, not email, but still). So i think it should resize to some point and then scrollbar should appear. Maybe input area shouldnt cover some % of chat window area or like.
In Psi resizing is going down stretching chat window (unlike in Spark, preserving chat window size and “eating” conversation part), and it goes down until window is hitting upper and bottom desktop sides, then scrollbar appears.