Buried deep within the changelog of Android 4.1.2 that arrived today is a very welcomed change to the way expandable notifications are handled by the OS. Introduced in Jelly Bean, expanding and collapsing notifications originally required two fingers to operate. Not anymore! A handy gesture now allows easy expansion and collapsing with just one finger, making it easier to perform this task while holding a device in one hand.
Collapsing is a little tricky at first and requires first pulling down and then up. Once you figure it out, it becomes a no-brainer, but is a little confusing if you don't know what you're doing. I think it would have been much easier to collapse by pulling up on the left side of any given notification where its icon resides, but the Android team chose a different approach.
The new feature is best demonstrated on video - let's take a look:
If you want to dig through the commit and the relevant code, here it is: commit 40c6ae4 - Single finger notification expansion.