The old search box could be resized AFAIK and with the new method of searching cuts of the search text. See below.
Here's what I'm using in this example to search for Album Artist and title, [SearchBy]=Album Artist and Title |$trim($if2(%albumartist%,$if2(%albumartist%,$if2(%album artist%,$if2(%band%,$if2(%albumartist%,$if2(%artist%,$if2(%artist%,%discogs_artist_name%))))))) %title%)|%s
It was not resizable but showed only the text entry and the label was in the dialog caption. I agree that this should not happen and I'll fix it to the next release.