At all.
Steps to reproduce:
1. Go to Adium --> Preferences --> Advanced --> Message History
2. Check the box "Show up to X lines of history in new windows"
X can be any number
3. Open a chat with someone
4. Send or receive a message
5. Close the window
6. Open a new chat with the same person
Expected results:
You should see the conversation you just had in that window
Actual results:
It appears as if you haven't had any recent conversations with that person
I am the only person, to my knowledge, that this bug is affecting.
It may not be easy to reproduce.
I'm running OS 10.4.9 on Intel.