`-moz-box` & `flex` at FF v112

[black7375]

Describe the bug

• https://www.reddit.com/r/FirefoxCSS/comments/11odffm/psa_incoming_changes_to_default_element/

As a part of the front-end technical modernization the old xul box model is being replaced with modern flexbox all around the UI.

Previously, just about everything used display: -moz-box but in Firefox 112 (at least in Nightly, but I would be surprised if this won't propagate to release 112 as well) the default display model will be changed to modern display: flex instead.

What this means first-hand is that all legacy box model -related properties will not do anything anymore so things like -moz-box-ordinal-group, -moz-box-orient, -moz-box-direction, -moz-box-align, -moz-box-pack or -moz-box-flex won't have any effect.

Expected behavior

No response

Screenshots

No response

OS

Linux

OS - Others

No response

Firefox Version

v112

Distribution

• [ ] Original Lepton
• [ ] Lepton's photon style
• [ ] Lepton's proton style

Theme

• [ ] Light
• [ ] Dark
• [ ] Alpenglow (System: Light)
• [ ] Alpenglow (System: Dark)
• [ ] System Default
• [ ] Others: (e.g. Photon Colors, Google Chrome Dark, Fairytale Of Nature)

Theme - More Info

No response

user.js setup

user.js setup

```javascript // Your settings ```

Additional context

• https://bugzilla.mozilla.org/show_bug.cgi?id=1820534
• https://groups.google.com/a/mozilla.org/g/firefox-dev/c/9sGpF1TNbLk/m/QpU3oTUuAgAJ
• https://crisal.io/words/2023/03/30/xul-layout-is-gone.html
• https://github.com/MrOtherGuy/firefox-csshacks/commit/0ff12e01fe18bc86ca68291c88c6dcf027cb9d83