I have one of these deadbolts on my front door. The bolt can be held back in the open position by turning the deabolt knob to the open position and pushing the bolt button up. It can also be double locked (the bolt will not open even by using the key) by pushing the bolt button up when the bolt is in the closed position. Although it is hardly high-security, it does present an interesting challenge, as I
can pick it (with a strong tension wrench) but have no idea how I would pick it with this bolt button in place.
I recently came home at 6am (after working all night) and found my missus had double locked the front door

Had to climb to the 2nd floor balcony and pick the ranch slider screen door......

lucky I even had my picks on me, or else I would have had to wait until 8am when she woke up......