title: Android launchmode="singleTask" does not work as expected
body: <p>I have an application that runs in the background and displays an error message via the notifications system. This notification has a pendingIntent that leads back to the app's main screen. On this main screen, I have set launchmode=&quot;singleTask&quot;. As I understand it from the Android Dev Guide, this should mean that my main activity will only ever have one instance.</p>
  <p>However, if the user is viewing that activity at the time (or another one within the app), and goes and touches the notification to clear it, it goes ahead and puts another copy of the activity on the stack, so if I hit the back button, it will return to the main screen again (from the main screen).</p>
  <p>Why would it be doing this?</p>