This software should allow the playback of MP3 files. The supported functionalities should be:
1. Play. Starts the playback of an MP3.
2. Stop. Stops the playback of the song and sets the cursor to the beginning of the file.
3. Play/Pause. Starts or pauses the playback of the *.mp3 file.
4. Next. Plays the next song in the list.
5. Previous. Plays the previous song in the list.
6. Volume control.
7. Add file/folder to playlist.
8. Randomize/shuffle play list (when playing)
9. Drag music in list to change playlist order
The central part of the window should display the playlist, which contains the songs added either via drag and drop or via the add file/folder option.