 
Device features while timing
If you have already started the stopwatch and want to use other device features 
while the stopwatch continues to run, simply press End to return to the standby 
mode. To return to the stopwatch, select 
Menu
>
Applications
>
Extras
>
Stopwatch
>
Continue
.
Using the stopwatch or allowing it to run in the background when using other 
features increases the demand on battery power and reduces battery life.