You can use Ctrl+W to close individual windows as well. Just a hint though: if you're using IE7 there was a bug with the Google Toolbar that stopped the "Open in new tab" feature working. I don't know if it's been fixed because I haven't downloaded the toolbar to try. Back to the original, I stopped using the "What is this?" feature quite a while back. I got sick and tired of getting "There is no help topic associated with this item." I figure if nobody's using it outside Redmond (or inside Redmond for that matter), why carry on supporting it?