You can set the maximum duration an application can be inactive before it's considered "idle." This is configured within the Application settings of a monitoring profile:
1. From the main menu, select Configurations > Monitoring Profiles.
2. Select the monitoring profile you wish to modify.
3. In the row for Applications, click the Edit 
button (found under the Actions column).
4. Enter your desired value into the Idle time threshold (minutes) field.
5. Click the Submit button to save and apply the changes to the profile.