Steps to reproduce the bug:
1. Open the IM window.
2. Reduce its height so only 4 lines show.
3. Select a group/user to IM (note the loss of 2 text lines due to the redundant group/user name titlebar and inconsistent line spacing).
4. Click the "detach" button to separate the IM session (note 5 lines again).
5. Click "attach" button (which needs its arrow pointing down instead of up, incidentally) to reattach the window.
Observed results: See above. The IM window resizes to include 5 text lines (instead of the original 4).
Expected results: Line amount should stay the same before/after a detach/attach.
http://tnlc.com/eep/sl/index.html#IM for more IM (and other UI) bugs/improvements.