Configuration: "Gestures lock everything", "do nothing when phone awakes", "lock everything when phone awakes on incoming call" (the latter should be irrelevant).
1. When on battery power, lock the phone using the gesture. Since it now cannot be turned off (the power button is locked too, might be another bug), let it turn off by itself.
2. Turn on the device using the power button - this is the only button that works when locked and that's good.
Result: The screen is locked as expected - but hardware buttons are not. The hardware phone button may easily get pressed twice, dialing the last-dialed number. The same happens when instead of step (2) a call is received - even during the call, any hardware button can be pressed to unintentionally answering the call or hanging up while talking (the same problem as in WM's native lock)...
Using HTC Touch Pro.