[Bug] privacy.resistFingerprinting causes the hover tab preview in content to be too small and offset

[bughit]

Abstract

privacy.resistFingerprinting causes the hover tab preview in content to be too small and offset.

It would be pretty silly for Mozilla to spoof various details for privileged extensions. That's meant for content. But that's probably what's happening. Is this something you can work around?

Steps to reproduce

1. Start Firefox with clean profile.
2. Install TST.
3. enable hover tab previews in content
4. set privacy.resistFingerprinting=true
5. open a bunch of tabs and hover on the last for the preview

Expected result

Actual result

Environment

• Platform (OS): win10 22h2
• Version of Firefox: 134.0
• Version (or revision) of Tree Style Tab: 4.1.1

[piroor]

Hmm, it looks impossible to be fixed by addon side... TST shows the tab preview panel with stable size even if the tab is shrunken by the user, with zooming based on the device pixel ratio information. The privacy setting you mentioned hides the device pixel ratio information to Web contents including privileged codes provided by addons.

[piroor]

I've found the sideway - the device pixel ratio can be calculated with tabs.Tab.width and window.innerWidth.

[piroor]

The scaling issue should be fixed with the commit 22c8905. But there still be another issue with its offset: the preview panel need to be shifted with the height of the sidebar header but it cannot be calculated with the privacy setting. Hmm...

[piroor]

I've decided to introduce a new expert option to configure the offset of the tab preview panel with the privacy protection mode, as a workaround.