But that is what the stock N810 does, if you don't use the lock/unlock slider.

Should I repeat myself? Do the following:

ONE: lock your N810. Either use the lock/unlock slider or wait long enough.

TWO: keep it locked Check: it is locked, right? Tap on the screen: nothing. Press keys: nothing. Make really, really sure it is locked

THREE: open the keyboard: tadaa!! the N810 is now unlocked Try it, just to make sure, press some keys, tap the screen, anything.

FOUR: close the keyboard. Don't touch the slider, just close the keyboard.

FIVE: your N810 is now locked! It's magic. No need to even touch the lock unlock slider! Open the keyboard: unlock, close the keyboard lock, open the keyboard: unlock, close the keyboard lock, open the keyboard: unlock, close the keyboard lock, open the keyboard: unlock, close the keyboard lock, open the keyboard: unlock, close the keyboard lock, open the keyboard: unlock, close the keyboard lock... etc. You may want to tap a rhythm of your choice when doing the open/close.