ShyFox Breaks Firefox's Letterboxing Anti-Fingerprinting

[BadgerInATrenchcoat]

Issue Summary

When using Shyfox, Firefox fills the available screen space with the website, regardless of the value of "privacy.resistFingerprinting.letterboxing" in about:config.

Expected Behavior

• Firefox respects the privacy.resistFingerprinting.letterboxing setting when set to true
• Website content is restricted to the standard bounds defined by the letterboxing functionality

Actual Behavior

• Firefox (with Shyfox) ignores the value of privacy.resistFingerprinting.letterboxing
• It fills the available screen area with the website content.

Additional Context

Letterboxing is a valuable anti-fingerprinting measure that helps reduce the unique data websites can access about users--in this instance, screen/window resolution. I have observed this issue to be consistent across multiple Shyfox and standard-Firefox profiles, to the extent I believe Shyfox to be the only possible remaining common denominator.