I think the search bar was just added to fill in the space, but the regular search link works no different than any other theme.
TheOriginalPinky , autumn : The last time I looked into it (over 3 years ago, lol) nesting is not possible on ProBoards forums, but it has been officially requested many times for future versions of the software. See Ulises' response in this thread for an explanation of why it would not be an easy task: support.proboards.com/thread/612445
NJtoTX : You can set BBCode as your default editor in all themes.
Although, as it turns out, I didn't realize my browser was zoomed in initially - I tend to a view a lot of sites at 125%, for more comfortable reading. At 100% zoom, the width doesn't go off the page; in fact, it's maybe a little too narrow. Making the Wrapper width something like 92% should make it flexible for different screen sizes, with a small margin on the sides.