To install this package, run in Emacs:
M-x package-install RET quarter-plane RET
This package provides Quarter Plane mode, a minor mode which provides Picture mode style editing (treating the screen as a semi-infinite quarter-plane). Unlike Picture mode, it is a minor mode (see the Emacs manual for the documentation of Picture mode). Type M-x quarter-plane-mode to enable Quarter Plane mode in the current buffer, and M-x global-quarter-plane-mode to enable it globally. In Quarter Plane mode, the commands `right-char', `forward-char', `previous-line', `next-line', and `mouse-set-point' are rebound to Quarter Plane commands. Known issues: Quarter-Plane mode doesn't work in read-only buffers, where it can't insert spaces. The user doesn't really care about the "modifications" of adding whitespace that's going to be trimmed when he exits quarter-plane mode or saves, but it's still part of the undo history. Both of these are due to the disconnect between what the user really wants--movement of the cursor within the window, regardless of where the text is--and what the mode can actually do--add dummy text to give the cursor a place to move to.