===== Issue 1 (2014-01-25_17.05.20.png) =====
What I expected to happen was...
Stair can't be placed
What actually happened was...
Stair could be placed
Steps to reproduce
Put a stair on the side of a block.
If you're standing in the lower half of the stair it won't disapear.
Sometimes it does disapear.

===== Issue 2 (2014-01-25_17.04.38.png) =====
What I expected to happen was...
Block can be placed/Box around stair is shown
What actually happened was...
Block can't be placed/No box around the stair is visible
Steps to reproduce
Look at a stair like in the attachment