Just to chime in on what's been said already...
Knock ON works regardless of launcher, and knock OFF with a 3rd party launcher would need a launcher with gestures supported, which in turn could be used to start the free screen off app mentioned above.
As you probably know, on the stock LG Home launcher, knock off works when you double tap an empty area of a screen. On a 3rd party launcher, what *LOOKS* like an empty area of a screen actually is not (as far as the knock off code is concerned). That empty area that looks empty because there are no icons there, is actually skinned by the launcher. To put it another way, the 3rd party launcher sees that spot as empty, but the knock code doesn't see it as empty, because the launcher is a skin over the entire area of the stock screens. That's why, the notification area works (or in my case, worked -- see below), because the launcher skin does not cover that notification bar area. Or possibly the notification bar floats over the 3rd party launcher; either way -- the result is the same.
Now, all that said... knocking on the notification area no longer turns the G2 off for me. It wants to open my Calendar as if I were making an appointment. I can see that the reason is that when i pull down the notification shade, the date/time are displayed there, so my taps are interpreted by the G2 as if I desired to set an appointment. I have not spent any time looking for the cause nor a workaround because I do have a empty area on every screen and have screen off installed and working. But it seems that the KK upgrade did affect my ability to knock off using the notification area; whereas I used to be able to do it before upgrading from JB.
Facebook
Twitter
Instagram