@@sharing causes reindexing of a possibly large amount of content without warning and without feedback

[zopyx]

Updating the @@sharing settings seems to reindex the complete subtree.
This can be very time-consuming for large subtree. No user feedback is given, no progress information is given.

For larger subtree (which can be determined using a catalog search against the 'path' index) there should be at least a warning. From the administrators point of view there should be some progress being writting to the Zope log file (the catalog has support for logging the progress of a reindexing operation).

[frisi]

the warning in case there is a lot of content within the current context sounds like a good idea.
we could also think about mentioning https://pypi.python.org/pypi/experimental.securityindexing in this warning