From Forum Nokia Wiki

User should be able to close all applications via device's task list. Task list is opened by pressing the Application key for a while. Then, use can select the application to be closed and press C key. This is important from the usability and user experience point of view as applications running in the background may consume a lot of memory and battery.

Being able to close the application via Task list is a requirement in Symbian Signed, check for test case number "Task List (UNI-05)" . Application that cannot be closed via Task list, won't pass the tests and therefore cannot be Symbian Signed.

• Application must not be closed via task list if its showing a dialog. So make sure that no dialog is showing during closing application via task list.

Solution

In order for an application to be closed through the Task list, it should handle the EEikCmdExit command either in the application UI or views. Independently of the current state, one of the application’s HandleCommandL() methods should react to EEikCmdExit and call Exit() on the application UI.

Note that an application cannot be closed through the Task list if it runs a confirmation dialog on exit, for example:

…
if(ConfirmExitL())
	{
	SaveL();
	Exit();
	}
…

where ConfirmExitL() displays a confirmation dialog. Consider removing the confirmation dialog, or running it only if the application is in the foreground. The above example could be rearranged as follows:

…
TBool reallyExit = IsForeground()?ConfirmExitL():ETrue;
if(reallyExit)
	{
	SaveL();
	Exit();
	}
…

where IsForeground() is provided by the CAknAppUiBase class.

It is also important to allow the framework to be able to close the application without user intervention, in cases of low memory for instance.

TSS000756 - Enabling notification about application being closed details the notification mechanism for the same. The event can also be captured in the HandleWsEventL function of the appui class if required.

void CYourAppUi::HandleWsEventL (const TWsEvent &aEvent, CCoeControl *aDestination)
	{
	switch (aEvent.Type())
		{
		case EEventUser:
			{
			//Check if this is a System's call to the app for shut down
			if (( *reinterpret_cast<TApaSystemEvent*>(aEvent.EventData())) == EApaSystemEventShutdown)
				{
                // Do something if required
                }
			}
            break;
		default:
			break;
       CAknAppUi::HandleWsEventL(aEvent, aDestination);
       }
	}

See also

• Common failures in Symbian Signed testing
• How to retrieve a list of currently running tasks