Easy possibilities to control currently playing music by "Music Play Dir" action

If music is playing by the "Music Play Dir" action it would be great to have other actions to control the currently playing music, most important:

• next song
• previous song
• play/pause song

But also actions like fast-forward would be nice.
I know it's currently possible to go to the next song by calling "Music Play Dir" on the same folder again, but this is not practical if there are many "Music Play Dir" actions for different folders and you want to have a single action to go to the next song everywhere.

Maybe easier alternative:
"Publish" currently playing music to the android system's API which is also used by other music players, which then listen to media keys and shows a little player in the notifications.