That's not a radical idea at all. Every other third-party file explorer from Resco, Xircuit, Aidem, and Vieka's PE explorer, etc all use the two window format (directory tree on top/filelist on bottom). Practically all the freeware explorers use the same approach as well.
The fact that Dan's Dexplor doesn't use that two-window format is what makes it unique.
If you prefer the two-window method of file access you probably should've went with the Resco file explorer instead.
If Dan started using that format, his file explorer would look just like everyone elses.