Let's say a user is running a program (for example a browser) on a 1920x1080 monitor but is only interested in columns 640-1919.
Hypothetically, this user suffers from epilepsy and has observed that the unholy flickering of certain advertisements in columns 0-639 occasionally triggers a fit.
Also hypothetically, this user feels environmental guilt over constantly and unnecessarily delivering electricity to 1/3 of the available (power-hungry) pixels.
Philosophically, this same user believes it a fundamental human right to have absolute control over what he wants to see and wonders why the operating system does not allow him to drag a virtual curtain over any uninteresting screen region.
Does such a Linux extension already exist?
If not, where would someone with only Android/Java experience begin study?