In the same vein as the distraction-free writ­ing” fea­tures of WriteRoom and PyRoom, a cus­tom color scheme for gedit can be ex­ploited to hide all text ex­cept for the cur­rent line. The ef­fect is some­thing like ADD Helper for your text ed­i­tor:

Distraction-free writing in gedit

For ease of use, a key­board short­cut can be mapped to a small script that tog­gles be­tween masked and un­masked color schemes.

Download the color scheme and tog­gle script.