Show dialog activity over another app from background
问题 Say you have an app A which opens up another app B (e.g. a map), which is not controlled by you (i.e. it's a preexisting app). So now app A is in the background. Suppose an event occurs and A wants to show a floating dialog over app B's UI (while leaving app B's activity visible behind it). Is this possible? (The usual answer to this would be to display a notification, but this is not a mass market app, and we are trying to get the user's attention very directly.) Currently, I was trying to