Fastmail "show details" broken

[eam]

• Facebook Container Version: 2.3.5
• Operating System + Version: Ubuntu 22.04.1 LTS
• Firefox Version: Firefox 104.0.2 (64 bit) Mozilla Firefox Snap for Ubuntu canonical-002-1.0
• Other installed Add-ons + Version + Enabled/Disabled-Status: Tested with all other extensions disabled. (I'd rather not share the full list if possible)

Actual behavior

Clicking on the "show details" link in the Fastmail webui does not show details (expanding From/To/Cc/Subject/etc beyond the first line).

Expected behavior

Clicking this link should expand the details in the fastmail webui

Steps to reproduce

1. Enable Facebook Container
2. Open a new tab and read an email on Fastmail
3. Click the "show details" link

Notes

I have been using Facebook Container on this platform for a long time without issue. I am certain a recent update caused this issue - within the last month or two.

[joshbode]

I have also have this exact issue (it also affects the folders drawer), which I've seen sporadically in the past (I even raised an issue with Fastmail support, but closed it when the issue went away). Note - this issue occurs in the Fastmail beta site (betaapp.fastmail.com) also.

It took ages to diagnose because even though I suspected an add-on (e.g. uBlock, Privacy Badger, etc), I never disabled this add-on, because... why would it have an effect on fastmail.com? :)

[joshbode]

It may be related to this CSS rule: https://github.com/mozilla/contain-facebook/blob/9ab4eb7c2f8ad535c0f171400903140083ab156f/src/content_script.css#L352

which matches the class is-hidden on the div for the sidebar:

<div id="v183" class="v-Split v-Split--left is-hidden" style="position: absolute; z-index: 1; transform: translate3d(-220px, 0px, 0px); inset: 0px auto auto 0px; width: 200px; height: 100%; will-change: auto;">

similarly for the "show details" button:

<div aria-hidden="true" class="v-Message-details is-hidden" style="height: 0px;">

[joshbode]

yep - the display: none style is definitely coming from content_script.css:

[neilj]

(I'm a developer at Fastmail.) It looks like this extension is also causing the message list to be scrolled to the top whenever you open an email. Why is this extension modifying anything on our site at all? Shouldn't it only be applying to Facebook's domains?

[joshbode]

@neilj #896 appears to fix this behaviour, too (I've just tested this in Firefox Developer Edition)

I suspect this extension applies to all pages indiscriminately because in theory, Facebook tracking can be embedded in any page (but of course, never Fastmail!) and I'm not sure there's a way to apply (or not apply) CSS to specific pages

[maxxcrawford]

@joshbode @neilj We reviewed the PR and merged it in. It will be a part of our next release!

Shout out @joshbode for the PR.

(Note - No exact word on immediate timing for that release, but I can estimate in the next few weeks)

[joshbode]

thanks @maxxcrawford :)

[dcelasun]

@maxxcrawford can you share a build here in the meantime? With signed extensions, it's no longer trivial to make local changes and the only alternative is to disable the extension. Neither sound great if the update is weeks away.

[krystian3w]

[!important]

Update addon to 2.3.10 or 2.3.11.

---

no longer needed after update addon to 2 3.10+

Maybe as fallback works: ```css .is-hidden:not([id^="fbc-"]) { display: revert !important; } /* !: but still break layout if webmaster enforce too low other value as initial/inherit. */ /* !: also no possible in that way detect new release new XPI */ ``` but to works need Stylus or: uBlock Origin/AdGuard (not "Lite => MV3" if you can not locally edit rules). ```adb ! AdGuard #$#.is-hidden:not([id^="fbc-"]) { display: revert !important; } ! uBO *#$#.is-hidden:not([id^="fbc-"]) { display: revert !important; } ```

[krystian3w]

5 months later: https://github.com/mozilla/contain-facebook/issues/898#issuecomment-1507446045

[joshbode]

Hi @maxxcrawford - is there anything we can do to help prepare for a release (testing a pre-release, for example)?

[joshbode]

Also, we can probably close this particular issue, because Fastmail has already worked around the issue.

[krystian3w]

I see someone pushed two new releases with fix for .is-hidden issue:

https://addons.mozilla.org/addon/facebook-container/versions/