Apply a Filter

The fastest way to select and apply (or reapply/refresh) a filter is to use the list box on the Filter Bar.

Select the filter and it is automatically applied to the article listings in the Thread Pane.
A filter can be refreshed or re-applied the same way (or Press F5).

Additional Notes:
If you do not see the Filter Bar, enable it with: View - Toolbars - Filter Bar
Alternatively, (but slower) you can access the filter list from the menu item: "Newsgroup - Filter Display …"
When working with a large number of headers (usually binary groups), refreshing or re-applying a threaded filter can take some time because Gravity has to re-thread and sort all articles every time the filter is refreshed.