1326924 - Firefox UI blinks when user applies lightweight theme (lwtheme)

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
1. Open about:addons
2. Hover mouse over suggested theme, move mouse away from the theme.
3. Hover mouse over the toggle button below suggested theme, click it.
4. Move mouse in a straight line [over the suggested theme, then outside of suggested theme]

AR:
 Step 2 - browser tabs blink.   Step 3 - browser tabs blink.   Step 4 - browser tabs blink.

ER:  No blinking in steps 3-4. Either X or Y
 X) Step 3 - Apparently, the theme has no default color. Well, if it had one, tabs would still blink.
             I expect that Firefox first downloads image, and only then sets image and default color.
    Step 4 - I already have that theme installed. Browser should do nothing.
 Y) Other ways to avoid blinking, suggested by Firefox developers, who know the browser better than me


Notes:
1) I _think_ it's reproducible on addons.mozilla.org, so it's not a regression of new UI
2) I added Step 2 to show that image being cached (or is it?) doesn't help at all.
3) If for some reason this was never reported, and you need to open follow-up bug, please make sure
   that it won't be resolved before this bug (otherwise this, original, bug may end up as "duplicate")

Comment 1

[:Gijs (he/him)]

What kind of "blinking" are you talking about, ie can you be more specific? I don't think I can reproduce what you're seeing.

Comment 2

[arni2033]

Attachment: screencast 1 - tabs blink when user applies theme.webm

Is it more clear now?

Comment 3

[:Gijs (he/him)]

Here's a still from the screencast:

http://imgur.com/a/lmcEK

There's no way this is just image caching or Firefox frontend code first doing one thing and then another. Looks like something in graphics/layout-land updates only part of the view and then another part. Milan, can you help figure out what's going on here?

Comment 4

[Jerry Shih[:jerry] (UTC+8) (inactive)]

I don't see this issue on win10-64 and firefox release 54.
And I can't ask for "[e-mail]". The email was disabled.
So, mark as worksforme here.