Pro tip: the Google Edition camera app can take pics with the volume buttons
If you didn't know yet, the Google Editions of the Samsung Galaxy S4 and HTC One have slightly updated features compared to Nexus devices with stock Android. The assumption is that they are giving a preview of some features we will see in Android 4.3, which is expected soon. One of the updated apps, the camera app, has already leaked out for adventurous users to sideload onto their devices; and, it brings along with it a feature we've been looking forward to in Android for a long time: using the volume rocker as the camera shutter button.
We had mentioned that the leaked camera app changes the UI slightly, but this is really the big update of the app: you no longer have to use the awkward holding position to be able to tap the on-screen shutter button. This means, when you (or your significant other, or whomever) is taking a selfie, you don't have to hope your finger is positioned properly to hit the shutter button rather than the home button (on a device with soft keys of course). Instead, just tap either the volume up or down key and your photo will be taken.
About time, eh?
source: Droid Life