title: Transparent, floating Android Activity doesn't allow updates to content behind it
body: <p>I have tried and tried to get a transparent, floating Activity to show up (as an overlay), but allow whatever is behind it to still show AND update. Right now it seems that if the Activity behind mine is closed or a new one opens (could be either in this case), the new underneath Activity does not shine through my Activity to the user.</p>
  
  <p>I have tried every combination of Flags I can come up with, and at this point I'm assuming Flags are not the answer. Can anyone help me find the proper code to do such a thing?</p>
  
  <p>Before anyone asks, I have a valid use case for this type of Activity; no, I don't plan to annoy the user with it.</p>