Just two small UI design issues:
Could the main tab headers and the search textbox have the same default system UI font as the menu and toolbar? I have configured it for the tab contents (9pt Segoe UI), but it's not possible for other areas. It still looks much like 8pt Microsoft Sans Serif, Windows XP's default UI font. (And this is Windows 7 here.)
And I think it might be practical to have a Clear Search button in the search textbox to quickly get rid of any search terms that are still left from earlier times. Such a clear button is used elsewhere, so why not also here. Right now I have no concrete suggestion about the icon to be used here though.