Sony Ericsson Xperia X10 :: Unlock Pattern Not Finished And Screen Turned Black

First of all this is minor Bug, but still - BUG! There is phone configuration description:
Phone: Xperia X10i
FW: android 2.1
patterns - default slider + unlock pattern

Bug description
1) When phone is locked, press home or power button.
2) move slider, to be able to draw pattern.
3) Start to draw pattern and wait till screen goes black (do not remove your finger). So your pattern is not finished and screen has gone black. Try to remember place of the finger.
4) Press home or power button again.
5) Finish unlock pattern from place you was, when screen turned black.
6) Your phone is unlocked!

So, if you did not finished your pattern and your screen have gone black you might think, that the phone locked, but this is not true. Your Phone can be Quite Easily unlocked in the Pocket.