Improve accessibility in the search UI

Whilst the search UI works for screen readers, it could definitely be improved with the following changes:
Firstly, make the "Search" combobox a required field.
Secondly, there is no easy way of navigating through results. I ended up tabbing though links, but it is then unclear when a new search result refers to a different library.
Finally, could this be made a modal dialog. Screen readers have two ways of navigating the web.
One essentially "flattens" the page in to a buffer so it can be read easily. Tyhe other, which is what we are dealing with here is used in a "live environment" where you have contents that change.

To fix this, we should either have a set of headings for each library the search has found, or have the user actually click a search button rather than the search being automatic.