Say you want to write a small shell script that locks up your GNOME desktop at specific intervals. What command would you use?
In this case, your best bet would be

gnome-screensaver-command –lock

This has the same effect as you pushing the Lock Screen button in GNOME. You can forge a small shellscript and use this to lock up your desktop when someone launches an application. Or append the line at the end of the Brasero launch command, using the icon’s command line field, so that whenever someone tries to burn something without your knowledge, the screen will lock up immediately afterwards. For example:

brasero && gnome-screensaver-command –lock

Put this in a new text file, make it executable and replace it’s icon with Brasero’s. Next time someone launches Brasero, after the application is closed, the screen will automatically lock up and you’ll know it was accessed by someone.