How do you create a Google Maps-esque drop down dialog?
<p>In the Google Maps application, when you open the menu and click on "Directions", it pops up a dialog that is unique to Google Maps.  It keeps the MapView in the background, but displays the search dialog from the top (or bottom, if you're on an old version of Android).</p>

<p>I was curious if anyone knew how they achieved this effect.  I'm willing to create a custom Dialog, but it seems that Dialogs are designed to pop into the middle of the screen (any other types of dialogs are denied permission as system dialogs).  What trick is Google Maps using?</p>
