Redmine

project activity should contain something like this:

@events += Message.find(:all, :include => [:board],
:conditions => ["#{Board.table_name}.project_id=? and
#{Message.table_name}.created_on>=? and
#{Message.table_name}.created_on<=?",@project.id,
@date_from, @date_to] )

Committed in r891.
Only new thread messages are included on the activity view.