This is an attempt to summarize posts in this thread:
http://www.rssbandit.org/forum/topic.asp?TOPIC_ID=1202
Read that thread for clarification if unsure.
In the "Options" on the "Display" tab add a "Hide
read items in category" or similar option to
the "General" section as a global default. Likewise on
the "Category" tab of the "Category Properties" dialog
add a similar option for a per-category folder
override.
When right clicking directly on the "Search Folders"
node in the tree add an option to the context
menu: "New Search Group" or similar. Likewise when
right clicking on one of these "Search Groups" have a
similar option.
When clicking on one of these "Search Groups" in the
tree show the combined results of the child searches.
Default app to "Hide Read Items in Category"
mentioned in first point above. Load into memory only
unread (and flagged?) items when clicking on
categories. When clicking on actual feeds though load
into memory all items from that feed only.
Hopefully that's a sufficient summary, if not follow
the link at the top. Thanx.