Usage report will show all activities recorded while you were working on the timesheet. To get this report, just create a timesheet, then switch to tab "Usage details". This will create a report, which will include only activities tracked during the time you were working on tags included in the timesheet.
You can export all the details or group the report by Groups or Title.
|Computer usage details during timesheet work|
|Retag a usage to remove it from timesheet|