As of a local m-c build from Oct 30, these display items are still doing fallback on gmail: AltFeedback Background BoxShadowOuter ButtonBorderBackground ButtonForeground FieldSetBorder ThemedBackground (plus event regions, but I have a patch to stop trying to create WR commands for that) The STR I used are: - build firefox with logging to record all the fallback items [1] in the content process - log in to gmail (enterprise gmail, using my @mozilla.com email address) - set the browser preferences to "restore previous tabs and windows on start" - restart the browser with WR enabled and pipe log to a file - once gmail loads fully close browser - grep log file for fallbacks [1] any item where http://searchfox.org/mozilla-central/rev/1c4901d060e3953e41088c038b62a0c026c1e1fb/gfx/layers/wr/WebRenderCommandBuilder.cpp#226 returns false

We do well enough for now.