[SOLVED] Sensors switched off by default?

if my app does a Bangle.setGPSPower(1), is GPS then always active even if I leave the app?

No, every time you do a long-press on BTN3 (or call load(..)/reset()) Bangle.js will turn all sensors off (apart from accelerometer, which is on all the time).

It's one of the nice side-effects of not trying to do fancy multi-tasking at the moment - each time you start a new app, everything starts up in the same state.