This could be implemented in a simple way for histograms or
ntuples, but not for all Root Trees because Hbook ntuples are
a subset of the functionality of the Root Trees.
If there are more than 5 people showing interest in the coming days,
we can increase the priority of this utility.
If there is a volunteer to do the job, we can tell him
how to proceed. There is no need to understand the internal
structures of either Root or Hbook.
Rene Brun