Retain only one copy of an activity on the stack when called from non-activity

How can I make sure I only retain one copy of an activity on the stack when called from non-activity?

When called from an activity I can just add the FLAG_ACTIVITY_REORDER_TO_FRONT flag to the Intent, but how can I do this from e.g. a widget or a notification?

From stackoverflow

• When launching an Activity from a notification, you're required to create a new task by setting the FLAG_ACTIVITY_NEW_TASK flag.

  Since you're required to do this, you can restrict that Activity to only having one instance by adding android:launchMode="singleTask" to its manifest entry.

  greve : That won't work the way I intend it to because if you select activity A, B, C and then A again, both B and C will be removed from the stack. Given that activity A has `android:launchMode="singleTask"` in the manifest.

  Christopher : Ah, true. I had the same problem with an app I worked on; I forgot that launching from a notification does indeed an existing history stack. And FLAG_ACTIVITY_REORDER_TO_FRONT doesn't help in this case (and furthermore is buggy on some devices). Bah.