I bought Knock2+ but couldn't get it to work for anything other than Google Voice on the HTC One. I emailed the developer but got nothing back so i've uninstalled it. Also, you have to activite it in the Accessibility settings and this causes the lock screen on Sense 5 to act differently. I use the stock Productivity lockscreen which should allow you to scroll through notifications without unlocking the screen but, it appears that on Sense 5, anything that requires activation in Accessibility causes the lockscreen to attempt to unlock at the slightest touch without needing to drag up. This might be cool for some but not with my lockscreen of choice. Just installed Missed Call/SMS Alert app. So far, so good but doesn't pop up anywhere or turn on the screen, it just plays a reminder sound.