Great work. I'm tempted to make this my default navigator, because I like the small font a lot.
I can only think of 3 suggestions for small improvements:
- make the sorting case-insensitive
- fix the bug where if there's an '&' in the directory path, the directory and any subdirectories won't be shown in the full path at the top of the screen (i.e. "SDCARD/Books/SC & E/Java" shows up as "SDCARD/Books")
- (if not too much work) use partial refreshes for selection