Discussion thread has started from https://bugzilla.mozilla.org/show_bug.cgi?id=1357306#c3. We should figure out a way to be able to pref on/off of Photon visual refresh change whatever using run-time or build-time approach.

In reply to bug 1357306 comment 13, how about if we land the patch that I pushed to that bug, but instead of enabling this for Nightly builds we keep it disabled. Then developers can enable it on their machines but official Firefox 56 Nightly builds will not have it. Does that sound better?

Yeah! Sounds great to me. Once we got Fx56 QA sign-off, we can enable the build flag in Nightly before the merge day. Please submit your patch here and let's land it! Thanks!

The patch I'm attaching enables the pref on Nightly. We can use Cedar[1] for testing the non-57 code. Cedar has been in use to see what Firefox 56 will be, which will have the various photon build flags disabled. [1] https://hg.mozilla.org/projects/cedar/

When this lands, what will we need to do to get the pref disabled on Cedar?

Comment on attachment 8887648 [details] Bug 1380585 - Add MOZ_PHOTON_PREFERENCES build-time flag to help with implementing visual refresh of preferences. https://reviewboard.mozilla.org/r/158532/#review163832

Comment on attachment 8887648 [details] Bug 1380585 - Add MOZ_PHOTON_PREFERENCES build-time flag to help with implementing visual refresh of preferences. https://reviewboard.mozilla.org/r/158532/#review163934 Looks great! And then we can add ifdef marco within css file to pref on the visual feature. ``` %ifdef MOZ_PHOTON_PREFERENCES ... %endif ```

Yes, that is correct.

Pushed by jwein@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/e79bfc74d149 Add MOZ_PHOTON_PREFERENCES build-time flag to help with implementing visual refresh of preferences. r=chmanchester,rickychien

Jared, how do you enable MOZ_PHOTON_PREFERENCES flag from mozconfig? Does it support artifact build?

The flag is enabled by default on local and Nightly builds. If you want to test without it, open /toolkit/moz.configure and set MOZ_PHOTON_PREFERENCES to default to False, like is done here for MOZ_PHOTON_ANIMATIONS and MOZ_PHOTON_THEME: https://hg.mozilla.org/projects/cedar/rev/b993c41fb851 QA will need to use builds from Cedar to test, as builds from Nightly will not actually be what ships in 56 because Nightly includes many Photon changes. All Photon changes are disabled on Cedar builds.

This is now disabled on Cedar, https://hg.mozilla.org/projects/cedar/rev/24f27a3637ac