I had this same issue for the past couple of years, but I recently found what I think is the perfect solution. I use a combination of the Media Buttons widget
and the Media Button Router app
. On my lock screen (using WidgetLocker) or on the home screen, I add Media Button widgets for previous, play/pause, and next, and these can operate any music player app that responds to Bluetooth controls. Then I install Media Button Router, which listens for a Bluetooth "Play" signal and pops up a list of available music player apps for you to select. So when I click the "Play" widget, I get a list of apps and I can choose whichever one I want to control for that session. Beautiful.
I have tested this with the following apps and it works great:
- Google Music Play
- MortPlayer Audio Books