impossible to map the "Play" and "Stop" button of OPZ to GroupTheLoop
I am almost there in order to synchronize my Op-Z (Teenage engineering) sequencer with Group-The-Loop app : it's indeed possible to map midi signals to trigger actions in Group-The-Loop...
Unfortunately, even though my OP-Z midi signals are going through the application, it seems like this app doesn't capture special MIDI events such as the one that OP-Z sends for "Play" and "Stop" 
Looks like Group-The-Loop does not catch "Start Clock" and "Stop Clock" midi signals
I almost found a workaround but it also failed : I can add on my Op-Z track a note on a silent midi channel (say, channel 15), so when the sequencer kicks-off, this note would trigger "Play" on Group-The-Loop...
But it failed again : it turns out that Group-The-Loop Triggers when the note comes back to OFF (Volume 0). And because the note I recorded on my sequencer cannot be of length 0, the trigger lags behind the beat of my OpZ :-(
- is it possible to trigger events on Note ON rather than waiting for the note to Be OFF ?
- As for Play and Stop : can you add the feature to capture MIDI "Start Clock" and "Stop Clock" ?
That would be awesome. I like this app but well... I am stuck