We had an issue that kept popping up: When you slid the preview bar and
the service couldn't start for some reason, it would start the service
over and over and over again. This would result in, for example, a
torrent of root mode permission prompts.
It happened because we sent the intent each time a touch was detected on
the slidebar. We don't need to do that, only when the first touch is
registered and the last touch is released.
Now that we don't check for root in all the places where Red Moon could
be started or root mode could be enabled, we need to guard against
trying to use the root mode filter when root is not available.
And we'll show a toast when that happens
Continuing the theme of "don't prompt people for root when not needed",
this time on the preferences screen — we only want to prompt if they
actually enable root mode, not when they open the preferences screen.
In order to do this, we need to make the root mode preference visible to
people on non-rooted phones. This is a good thing! Otherwise those
people wouldn't know the feature exists; maybe some of them will be
motivated to root their phone!