This is a FileMaker time-tracking file. It functions much like other time-tracking applications. Using a FileMaker file allows you to use its powerful features for creating reports, and for itemizing custom categories and "phases" of a job however you want.

There are 3 buttons that you use with a session. The first, from the left, the light bulb, is the "Start" button. It disappears when you begin a session.
The second button, which is usually a wrist watch, is the "Restart" button, to continue the current session (after it has been stopped).
The third button (usually blank) is the "Pause" button. When a session is going, it changes to a coffee cup. When pressed, it begins tracking the paused time, until you click it again, to return to tracking.

The big red dot shows the status of the current session. When a session is tracking, it turns to green. When you pause it changes to yellow. Stopped is red.

Tracking time it looks like this.

Paused it looks like this.

The final stopped time, showing elapsed time.

All of the above views are of a single entry. There is of course a full list view, like any other FileMaker file. There is also a "minimized" view, which shows only the essential data and the buttons, and a summarized print report.

The big Close button, by the way, will alert you if there's a time running, in case you want to stop it first.

The timer is not running a script. It's just intelligently tracking when you start, pause or stop. This requires no processing power to do in the background.