Hello pswebsitedesign,
Thanks for contacting us. From what I can tell, this is what you want, yes?
The short answer is “no, we don’t support that”. If you have a moment, we’d love for you to submit your idea to our UserVoice forum. We take user ideas and contributions very seriously, and many times their ideas end up in our future releases.
The long answer is “yes….. maybe….” with quite a bit of creativity. A developer may be able to add something with our filter api and Themer’s Guide, unfortunately that level of customization goes well beyond the scope of the forums.
It’s worth noting, that the filter bar has a horizontal view, but I don’t believe that is what you want. It still wouldn’t be a unified search box.
Sorry I didn’t have a better answer!
– Casey Driscoll