registerBackButtonAction now for the first time:
Only in special cases (when user switched internal (=non-ui-router) states of the current view, the Android back-button should not execute default action (go back to previous view).
But there’s a problem: once registered (priority
IONIC_BACK_PRIORITY.view + 1) it is the only handler which will be called.
Would be nice to have something like “event.backButtonHandled = false” and let ionic call lower prioritized handlers, in this case
Otherwise I have to handle “back” on my own, with potential divergence of the behaviour.