Prevent multiple instances

[dmnd]

via email:

Thank you for your Caffeinated program, it's working out great for my in-law that was getting annoyed with her computer going to sleep while letting her music play. I do have a feature request however. My in-law keeps pinning Caffeinated to the task bar and opening multiple instances of the program instead of going through the system tray. Can the program be changed so that if the program is run again while already running, to just bring the current instance to focus instead of making another?