The Preview window layout is terrible for wide windows.
Ding and HS2 produced a "tagwin bottom style" patch that's available in the forums.
It's long past time for something like that to make it into the official version.
Some of us dock the Preview window at the bottom, and have it very wide but not very tall.
The stock Preview window is unusable in that configuration (you get to see about 3 or 4 lines of code).