Boy Locks Himself in Hidden Room and Watches Through Walls

by Mick
(Merced, California, USA)

What is the name of the movie where a young kid accidentally kills a girl that's teasing him by pushing her onto a brick on the ground?

The boy then hides in his room which he has walled off from the rest of the house.

His parents either die of old age or he kills them, and new people eventually move into the house.

In the end, the boy is looking through a hole in the wall at night. He then charges out and eats grass on front lawn.