This is a really nice feature; the ability to Preview a Filter or Group directly within your Search Center. A lot of folks like this because it lets them see more information about the Contacts within a Filter than the Preview Tab in the Filters window.
To do this;
1. Open up your Search Center by clicking on "Search" from the top Toolbar
2. Click on the Filters/Groups button on the top "strip" of the Search Center
3. This will open up a Filters and Groups pane along the left hand side, in a tree format
4. To Preview any Filter or Group, simply doubleclick on it
5. GoldMine will prompt you whether or not to apply a "limit" on the Previewed Filter or Group. This is not required. If you'd like to see the entire contents of the Filter / Group, simply click "No"
Your Search Center should now be showing you all the Contacts within the Filter / Group. Keep in mind that your Previewed Filter is "activated" within the Search Center at this point, and to Release it, you must eventually right-click within the Filters and Groups pane on the left hand side and select "Release Preview".