DECALN Screen Alignment Test

Fill every cell of the screen with an E. It was meant for adjusting the focus and linearity of a CRT, and it lives on because it is the quickest way to put something in every cell: many of the cases on this site start with it before erasing or scrolling part of the screen.

Along the way it resets the top and bottom margins, and the left and right ones, to the whole screen, and moves the cursor to the top-left.

Validation

DECALN-1: Fills the screen

\e[2;3H
\e#8

|EEEE|
|EEEE|
|EEEE|
cursor 1,1

DECALN-2: Resets the scrolling region

\e[1;2r   # region is lines 1 and 2
\e#8
\e[2;1H
\n        # would scroll if the region were still set

|EEEE|
|EEEE|
|EEEE|
cursor 3,1