Retrieve data in the background

@PiOfThings is spot on here. I'll be coming up with some proper tutorials soon and I'll try and cover this.

But right now, Widgets are your answer. The GPS Recorder widget is probably a good place to start: https://github.com/espruino/BangleApps/tree/master/apps/gpsrec

It:

• Has an app that lets you configure it
  
• Has a widget that runs in the background and (when enabled) starts logging data
  
• Has an 'interface.html' file which runs inside the App Loader and allows it to read back the recorded data.
  
  

There are a few gotchas:

• There's no way to leave code permanently running as you change apps - right now it's a design choice because I think at least initially it's important that the watch is really stable (and that means always bringing apps up in a known state). You can respond to a kill event to save state and reload it later though.
  
• Not all apps will actually load widgets (games won't for example) so your stuff won't run in the background in that case. I'll be working to modify more apps to make them load widgets where it is sensible to though.