Mobs and walls and other mobs

I personally would like to see mobs be more solid. Several times I've seen them move through other mobs, including my own summoned creatures. Also, this:

http://img687.imageshack.us/img687/6568/dodbug1.png

I had to punch a number of holes in this wall (thanks to Golemancy) to find this quest mob, and it only appeared -after- I walked in to blast another hole. Of course, it was spawned via placing a quest item on the Mellow Shrine.

 

There's also a bug which occasionally allows you to stand on the same space as a monster:

 

I have noticed that walking and tapping space increases the chances that you will walk through a monster or land on the same square as a monster.