The Workflow Filter in WEBLiNK allows you to restrict access to TWiST workflows based on user or group.  First, make sure that the user or group that you want to filter is assigned to a Role that has the WEBLiNK option 'Can see all workflows' disabled, as having this enabled will supersede anything set in the Workflow filter.  Next, log in as a user with a System Administrator role (such as root), and click on the 'Workflows' icon in the menu bar.  You'll get a list of workflows in alphabetical order.  Click on the shield icon before the workflow's name to access the Filter settings.  This will open a window with two columns: on the left, a list of all users and groups, and on the right, the users who are authorized to use the workflow.  To add a user or group to the authorized list, highlight their name in the left-hand column and click the top arrow (the one pointing to the right-hand column).  The user or group will now appear in the Authorized Users column.  To take a user off of that list, highlight their name and click the bottom arrow (the one pointing to the left-hand column).  Please note that you cannot select multiple users or groups!  Once you have finished making your list, click on the checkmark in the upper right-hand corner to apply your changes.  No restart of Tomcat or Java is required - the changes are made automatically, and your users will be able to access the selected workflows on their next log-in.