(source: Iceberg Slim – Pimp, The story of my life)

“The steel door was half open. That screw would be out at any second to hook the shed door. There was no place to hide. It had been all for nothing. I heard a voice and the scrape of feet at the steel door. The screw was coming out into the shed! I looked up at the shed ceiling. I looked over the steel door. There was a line of rusty bars a foot long over the door flush against a grimy window. I leaped up and grabbed two of them. I swung my feet and legs up just as the screw walked in to lock the door. I was jack-knifing my legs just six inches from the top of his blue uniform cap.”

Background:

Slim tries to escape from the jailhouse. First he hides in a little depot-like room (“shed”) and plans to wait for the night there and climb over the wall in the darkness. The little shed is connected to the bath with a steel door. Slim got in a dangerous situation because a guard came into the shed to close the outer door, but the room was empty and offered no place to hide. At last Slim recognized a barred window above the steel door. He managed to grasp the bars and pull himself up completely before the guard came in.

What I do not understand in the description is the “door flush” What part of the door is this?