This is a margin issue in the manager css file. Did you file a bug report? You can fix this if you change the #treeholder inline style to width of 220px and the manager css file entry for the padding of the #treeholder to 5px 20px 0;
Author of zero books. Formerly of many strange things. Pairs well with meats. Conversations are magical experiences. He's dangerous around code but a markup magician
Thanks, Jay. I had not filed a bug report, actually. It appears that this is a known issue, though?
I tried your solution but found that once #treeHolder is resized, the fix is reset. Instead, I set the width of #treeSplitter (in the manager css file) from 10px to 1px and it fixed the problem.