generate orphan processes if use keyboard shortcut to start application, which has 1 instance already

[yanglei]

Steps:
1. launch application (e.g. calculator) via desktop plugin
2. do some operations to change default app interface ( e.g. input some digits in calculator)
3. click "home" to hide the application window
4. use key shortcut to launch same application (e.g. shift+ctrl+c for calculator)

    at this time, you can see a new application instance (e.g. new calculator window without input number) launched

5. in console, use command to check the application process id
    e.g. ps -ef | grep galculator

    at this time, you will see 2 galculator process shown:
    one of process have parent process ID of 1, this means the first launched instance become orphan process.

For handheld devices, this may cause init process (PID=1) becomes overloaded by too many orphan process.