How to take a screenshot on Android 4.4.2 on a Nexus 4? I read that you need to hold the volume down button and power button simultaneously to take a screenshot. I've tried this many times and I just can't get it to work. Most of the time the volume lowers, sometimes the screen locks.

Update: Sometimes it's very easy to take screenshots, but usually it's impossible. It's likely a hardware or software defect. Many times I'm also unable to unlock the screen on my Nexus 4. I'm confident it's not a timing issue.
If the buttons don't work, you could always try using ADB from a computer. Root is not required but USB Debugging must be enabled. Then just run:

adb shell screencap -p /sdcard/screen.png
adb pull /sdcard/screen.png
adb shell rm /sdcard/screen.png


These commands will produce a screenshot and save it in the sdcard directory (on some devices, including the Nexus line, have an emulated sdcard partition in the internal storage; so don't worry about this), pull to your computer, and then deletes it from your phone. 

Unfortunately, one would think that this would be easier on stock Android. But that's why so many aftermarket versions or apps exist: to provide the missing functionality that people can cherrypick from and customize as they please. Below is an example of a simpler and nicer interface from which to take screenshots, which was added to stock 4.4.3 Android using GravityBox [KK] (root and Xposed required).