This project is abandoned and its default file will likely not work with the most recent version of World of Warcraft. Whether this project is out of date or its author has marked it as abandoned, this project is no longer maintained.
An extremely simple addon that simply gives you a text display of how much your Shield Barrier absorb will be worth if you activate it at any given moment.
Options can be found in the Interface -> AddOns menu.
Configurable font (via SharedMedia), font size, color, and position.
Is there a way to make this addon disable itself or at least hide the onscreen display when I'm not in prot spec?
Does this vary the result by the amount of rage the player has?
Yes.