Affected versions

• 88.0a1 (20210307213430)

Affected platforms

• macOS 11.2.2
• Windows 10x64

Preconditions

• enabled proton toolbar

Steps to reproduce

1. Open Firefox Customize mode.
2. Add Zoom controls and some elements before.
3. Change Zoom levels between 100 and 90.

Expected result

• Elements before zoom controls are not moving.

Actual result

• Elements are moving.

Regression range

• I will search for one ASAP if there is one.

Notes

• Attached a screen recording.

It seems that the elements are moving as well even if zoom is increased by clicking + button several times. Attached a screen recording.

I can't personally reproduce this, but Blake can. Also appears in the app menu

I also can't reproduce. Better steps would help narrow down a regression window as well... If from the regression window it's easy to fix (and it sounds like it's not happening on non-proton) then presumably this is fixable by restoring a fixed width for the "reset" part of the control, which I assume is applied without proton, but not applied with proton. Either way, considering this control isn't normally in the toolbar and this problem primarily happens when changing the number of digits of the zoom level, and then only in some cases, this isn't high priority. It'd be S4 except I've realized that this probably means the toolbar can "jitter" when switching tabs in this configuration, which I imagine would be highly annoying.

Hi!
The steps for this, at least for me are:

1. Open Firefox with a clean profile having the proton toolbar enabled.
2. Enter Customize mode and add Zoom Controls in front of the Downloads button on the right side.
3. Add two more random items in front of the Zoom Controls.
4. Save changes and change Zoom Levels between 90% and 100%.

This issue is reproducible with Normal and Touch mode density, but not with Compact mode. Another thing worth mentioning is that the issue can be seen when switching tabs with different zoom levels (under/over 100%). Attached a screen recording.

Regression range with proton toolbar enabled:
Last good revision: 90df77c721dd9353439673063e2c96e885119153
First bad revision: 05b20fdef40d726358e98bb0b4d53f4443ead977
Pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=90df77c721dd9353439673063e2c96e885119153&tochange=05b20fdef40d726358e98bb0b4d53f4443ead977

Also, I found out that the issue is reproducible with the proton toolbar disabled while having Touch density enabled but not with Normal and Compact mode. Let me know if a regression range will help with touch mode and proton toolbar disabled (if there is one). Thank you!

Previous calculation did not take in account padding of toolbar button, so this now uses 4ch + 1ch + var(--toolbarbutton-inner-padding) * 2.

The component has been changed since the backlog priority was decided, so we're resetting it.
For more information, please visit auto_nag documentation.

https://hg.mozilla.org/mozilla-central/rev/22545dd0b232

Verified fixed with Firefox 88.0a1 (20210321213736) on Windows 10x64, Ubuntu 20 and macOS 11.2.3. The elements before zoom controls are no longer moving when changing zoom levels.