title: Display a "help" overlay over an Android layout
body: <p>I'm working on a game for the Android (Sky Hiking - <a href="https://play.google.com/store/apps/details?id=com.rachum.amir.skyhiking.android&amp;feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5yYWNodW0uYW1pci5za3loaWtpbmcuYW5kcm9pZCJd" rel="noreferrer">Google Play</a>, <a href="https://github.com/Nurdok/Sky-Hiking" rel="noreferrer">Github</a>). I want to add a "help" option for the game where it'll go over the game components one by one, point to them with an arrow and have a text box say what they are used for. I'm looking for advice on what's the best way to achieve this. Should I display a huge (partly transparent) image over the game activity which contains the arrow (I will need an image for each arrow for each component of the game).</p>
  
  <p><strong>Edit</strong>: There's also an issue of doing this for different screen sizes.</p>
  
  <p>What's the best practice on this one?</p>