I know that there are News Filters, and i use these, but sometimes I just want to do a once off search on all my feeds. I can do this per feed or per folder, but i don't believe that it is possible to do it globally?
Create "root" folder. Drag all your folder into created one. Choose root folder. Use search as you wish.
Create "root" folder. Drag all your folder into created one. Choose root folder. Use search as you wish.