1423935 - flickering when creating new windows with custom theme enabled

Status: NEW

(WebExtensions :: Themes, defect, P3)

Description

[:glob ✱]

Attachment: 2017-12-07 22_19_07.mp4

59.0a1 (2017-12-07) (64-bit) on OSX

steps to reproduce:
1. install https://addons.mozilla.org/en-US/firefox/addon/quantum-lights-dynamic/
2. create a new window

expected result:
new window opened with theme already applied

actual result:
massive flickering.  see attached movie.

stepping through the frames it looks like the following is rendered:
1. solid aqua background (default for theme?)
2. my previous theme (https://addons.mozilla.org/en-US/firefox/addon/quantum-launch)
3. quantum-lights-dynamic
4. solid white background
5. quantum-lights-dynamic

Comment 1

[Jared Wein [:jaws] (please needinfo? me)]

This theme is using the Themes.update API after the window has been created to set the styles on the window. So I don't think we can 100% get rid of the flickering but we should be able to remove steps 4 and 5 from the list in comment #0.

Comment 2

[Florian Quèze [:florian]]

(In reply to Jared Wein [:jaws] (please needinfo? me) from comment #1)
> This theme is using the Themes.update API after the window has been created
> to set the styles on the window.

Is it a bug of the theme or a problem with the provided theme API that these styles set by the theme on the window can't be applied before first paint?