Mediaplayer-like application (one instance, commands)

[godlike_panos]

Im trying to imitate a certain functionality the media players usually have. Imagine that you have a media player already running. If I double click an mp3 in your desktop the media player will not invoke a new instance but it will understand that its already running and it will simply add the mp3 in the current playlist.

My question is how (if possible) can I do that using Qt4? How will I understand that the application is already running and how can I send commands to that application?


Thanks in advance!!