1699577 - With the Proton theme, overflowing the tab strip moves pinned tabs slightly to the right

Status: RESOLVED DUPLICATE of bug 1696438

(Firefox :: Theme, defect, P3)

Description

[Robin Steuber (they/them) [:bytesized]]

STR:

1. On a fresh profile, set browser.proton.tabs.enabled = true and restart the browser.
2. Make sure the browser window is maximized.
3. Pin a tab
4. Notice that if you click in the very top right corner of the screen, you select the pinned tab
5. Open many new tabs. Enough to expose the overflow arrow buttons on the tab strip.

Expected Results:
The pinned tab does not move. Clicking in the very top right corner of the screen should select the tab, as it did previously.

Actual Results:
The pinned tabs shift slightly to the right so that clicking in the top right corner of the screen does not activate the pinned tab

Additional Notes:
I'm running Windows 10, if that's important.
The reason that I noticed this is that it seems to interfere with muscle memory that I didn't realize I had developed. My left-most pinned tab is always my email. Apparently I developed the muscle memory to click right in that corner when I want to get to my email.