Comment 3 for bug 1531167

It is a feature to prevent pocket dialling.

Use cases are:
With the phone in your pocket, receive a notification which would wake up the phone then you don't want to inadvertently (by touching the phone with your pocket):
- enter a wrong SIM code and lock you card
- enter a wrong PIN code/pass code and lock your phone
- Call an emergency number
- Do all sort of unexpected actions if your phone is not protected by a code.

does it make sense or do you have other expectations?

The screen going crazy is another issue and I couldn't reproduce it.