1364290 - 1.89ms uninterruptible reflow at insertPlaceholder@resource://app/modules/DragPositionManager.jsm:181:7

Status: NEW

(Firefox :: Toolbars and Customization, defect, P4)

Description

[Hazel Ward]

Here's the stack:

insertPlaceholder@resource://app/modules/DragPositionManager.jsm:181:7
_setGridDragActive@resource://app/modules/CustomizeMode.jsm:2101:5
_setDragActive@resource://app/modules/CustomizeMode.jsm:2019:9
_onDragStart/this._initializeDragAfterMove@resource://app/modules/CustomizeMode.jsm:1623:11
_onDragOver@resource://app/modules/CustomizeMode.jsm:1641:7
handleEvent@resource://app/modules/CustomizeMode.jsm:1490:9
EventListener.handleEvent*_addDragHandlers@resource://app/modules/CustomizeMode.jsm:1086:5
enter/<@resource://app/modules/CustomizeMode.jsm:355:7
TaskImpl_run@resource://gre/modules/Task.jsm:319:42
process@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:922:23
walkerLoop@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:806:7
Promise*scheduleWalkerLoop@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:739:11
schedulePromise@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:770:7
completePromise@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:707:7
deferredWrapToolbarItem/</<@resource://app/modules/CustomizeMode.jsm:863:9

DragPositionManager.jsm:181:

      aContainer.lastChild.getBoundingClientRect();

Comment 1

[Andrew Overholt [:overholt]]

Customize mode = not-super-urgent so p3

Comment 2

[:Gijs (he/him)]

This is going to be annoying to fix, because the layout flush is deliberate to make a 'notransition' attribute take effect. I wonder if we can rewrite this so that it's not necessary...

There's identical code in https://dxr.mozilla.org/mozilla-central/rev/6ff60a083701d08c52702daf50f28e8f46ae3a1c/browser/components/customizableui/CustomizeMode.jsm#2142-2146, which somewhat surprisingly I don't see any other open bugs on file for.