I would like to see two additional features added to make Library Search more useful.
Permit multiples instances of the Search box in the toolbar. This would allow, for example, both an “Anywhere” and a “Filename” search box. Those are the two I use all time.
Keyboard shortcut directly to the Search options (e.g. Anywhere, Filename, etc.). There is a keyboard shortcut to Search, but it just puts the cursor in the search box, with the setting as it was. Changing the search box setting requires going to the mouse, as far as I can figure out, anyway.