The original code used to 'update' the tree view with responses from the
phone every time a user expanded a directory. This meant that if a portion
of the tree view was not queried it would remain unchanged. The way it is at
the moment all subdirectories under a directory being expanded are deleted
even if they are not queried from the phone.
I don't think the way that this is implemented at the moment looks very good
visually, regardless of the accuracy. Collapsing a directory with expanded
subdirectories and re-expanding causes the subdirectories to briefly show
their original contents before they disappear, it would be better if they
never appeared at all. Personally I prefer the original way of only updating
the parts of the file system that have been queried from the phone rather
than deleting all and starting again. This is way that filesystem viewers
work on windows and linux and would be what users would be expecting.

Simon