To make it clearer which filters are active and which particular flight triggered an alert I have updated SquawkBox. Any filters that are configured are now displayed in full in the title bar, e.g. "SquawkBox - Connected - Filter(Show:7500,7600,7700,4000-4600)" instead of just showing "SquawkBox - Connected - Filtered" as before.
When an alert is triggered the squawk code and the flight number of the flight that triggered the alert is added to the title bar, e.g. "SquawkBox - Connected - Code: 4375, Flight: BMA5HY triggered alert - Filter(Show:7500,7600,7700,4000-4600)". Where the flight number is not available then the registration is shown instead. If that's not available then the modeS is shown. This alert text remains in the title bar until the alert is cancelled via the "Cancel alert" menu option.
This update is on the SquawkBox website at
http://www.gfrost.co.uk/SquawkBox/. To get this new feature it is only necessary to replace the exe file if you already have SquawkBox installed.