Click 'Search' at the top right which then gives you an option for Advanced Search where you can select only the Watcher Forum to search if that's what you were looking for?
In any case, the answer is the new background mode that was added in the last update. Choose the 'Enter Background Mode' option from the FTP Watcher menu bar icon.
Having said that, I had some reports of there being some issues with this new feature and there is an update coming to sort those out. If you have difficulty let me know and I'll send you a pre-release.