1782726 - Kiosk mode briefly displays the normal UI with URL bar

Status: NEW

(Firefox :: Enterprise Policies, defect, P5)

Description

[J]

Steps to reproduce:

Start Firefox in kiosk mode:

firefox.exe -kiosk http://127.0.0.1/

Actual results:

Very briefly (during less than 500 milliseconds), the "normal" Firefox user interface (with URL bar etc.) is displayed, before disappearing and going in kiosk mode.

Expected results:

In order to have a perfect kiosk mode, we would expect to not see a flickering with the URL bar.

Comment 1

[J]

Attachment: 20220802_161101_d0c8ac8f.png

Screenshot

Comment 2

[J]

Comment on attachment 9288110 [details]
20220802_161101_d0c8ac8f.png

This is visible during less than 500 ms, but it shouldn't be visible at all in kiosk mode.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Firefox::Address Bar' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 4

[J]

Linked: https://bugzilla.mozilla.org/show_bug.cgi?id=158968

Comment 5

[:Gijs (he/him)]

The kiosk mode support is covered by our enterprise policy support; hopefully they can take a look. Maybe this is an issue with the skeleton UI or something - Mike, do we disable that when called with -kiosk? If not we probably should.

Comment 6

[Mike Kaply [:mkaply]]

Skeleton seems like a likely candidate. I'll take a look.

Comment 7

[Mike Kaply [:mkaply]]

I see a flash, but nothing close to 500 milliseconds. What platform are you on?

Comment 8

[J]

Yes it is a flash. Note that I said "less than 500ms" because I did not measure precisely. It is perhaps 100ms, I should do a screen recording to have a more precise estimation.
I noticed this on Windows, but I think it is the same on Linux.

One key feature for a kiosk is that the end-user is in a closed environment. If they see the usual Firefox interface (even if only during 200ms), then it diminishes the polished look of a kiosk application.

Do you think there is a command-line option to prevent this to happen?

Comment 9

[Mike Kaply [:mkaply]]

Do you think there is a command-line option to prevent this to happen?

There isn't. The reason it happens is because we're switching Firefox into full screen mode at the first opportunity, so that will be Firefox UI for very small amount of time.

Comment 10

[J]

I see.
Can we set this full screen mode before the first window "paint"? (WM_PAINT in Windows terminology if I remember correctly) https://docs.microsoft.com/en-us/windows/win32/learnwin32/painting-the-window

Comment 11

[Mike Kaply [:mkaply]]

Because of the way kiosk mode is implemented, I'm not sure that's practical. I added it as early as I could.

Comment 12

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:mkaply, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 13

[Negritas Sergiu, Desktop QA]

Hello I have managed to reproduce the issue with firefox 108.0a1(2022-10-20) and 107.0b2 on Ubuntu 22.04. I will mark this issue as NEW and update the flags.

Thank you!

Comment 14

[J]

Thank you @NegritasSergiu!

Does someone have an idea about a fix for Firefox in Kiosk mode?

Comment 15

[J]

(In reply to Negritas Sergiu from comment #13)

Hello I have managed to reproduce the issue with firefox 108.0a1(2022-10-20) and 107.0b2 on Ubuntu 22.04. I will mark this issue as NEW and update the flags.

Thank you!

Thank you @NegritasSergiu!

Does someone have an idea about a fix for Firefox in Kiosk mode?

Comment 16

[Mike Kaply [:mkaply]]

I don't have any good ideas on how to fix this at this time.