Your last use-case is sort of covered by Android's screen pinning feature[0]. You have to enable it in settings, but it's useful, and seems to work well. [0] h

Your last use-case is sort of covered by Android's screen pinning feature[0]. You have to enable it in settings, but it's useful, and seems to work well. [0] https://support.google.com/nexus/answer/6118421?hl=en https://support.google.com/nexus/answer/6118421?hl=en This link is for Nexus, but I think it's included in all version of Android since 5.0 Lollipop.