1616861 - Background window contents are huge when switching from native MacBook retina to attached non-retina display

Status: NEW

(Core :: Widget: Cocoa, defect, P2)

Description

[Heath Borders]

Attachment: background-window-oversized-1080p.mov

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:72.0) Gecko/20100101 Firefox/72.0

Steps to reproduce:

I don't yet have good reproduction steps. This seems to happen mostly when I plug in my MacBook to its docking station after it's been disconnected for a while. This opens Firefox windows directly onto a non-retina Apple Cinema HD display.

Actual results:

Firefox windows in the background have extremely large contents. They seem like they're still being rendered for a retina display, but inside a non-retina window.

When I click on the background Firefox window and move it to the foreground, the contents re-render themselves properly.

Expected results:

Background Firefox windows should render properly immediately.

Comment 1

[Heath Borders]

In the attached video, the window is technically in the background (I moved other foreground windows out of the way so you could see the entire background window). When I click on the background window, it comes to the foreground and re-renders properly.

Comment 2

[Augusto Pace]

Hi,

Unfortunately I was not able to reproduce this issue. Anyway I'm setting component to Core - Graphics for someone to take a look at this.

Meanwhile @[e-mail] could you please try on our latest Nightly build? You can download it from here https://nightly.mozilla.org/ Also can you try this in SAFE MODE?

Thanks.

Comment 3

[Heath Borders]

I'm running https://npr.org and https://stlpublicradio.org in separate windows in SAFE MODE on the latest nightly build. Usually, this happens when I switch between my external display and laptop's native display. I'll let you know when I see it again, and try to get a better handle on when it changes.

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Markus, is the behaviour here expected? What happens in Firefox on DPI change? Is this just the tab lagging behind?

Comment 5

[Heath Borders]

Attachment: background-window-oversized-nightly-safe-mode-1080p.mov

It happened again on Firefox Nightly while running in Safe Mode. It only happened on one of the windows though. The other window was appropriately sized.

Steps:

1. Open Firefox Nightly while on an external display
2. Disconnect from the external display for 2-5 minutes
3. Open MacBook Pro and use native retina display without an external display connected. Don't foreground Firefox Nightly
4. Close MacBook pro for 2-5 minutes.
5. Connect MacBook Pro to an external display, and wait for it to show a login screen. Keep the MacBook pro itself closed so that the native retina display isn't active.

Comment 6

[Heath Borders]

I was able to replicate it again with simpler steps.

1. Foreground Firefox Nightly while on a native MacBook Retina display only
2. Put other apps in the foreground so that Firefox nightly goes to the background, but is still visible.
3. Close the MacBook, and while it is still closed, connect it to an external display.
4. Firefox nightly will render huge contents while in the background.

Comment 7

[Markus Stange [:mstange]]

I'm moving this bug to Widget:Cocoa because that's where most of the other bugs of the type "Firefox is pretty bad at dealing with mixed HiDPI / non-HiDPI monitor scenarios" are.

Comment 8

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

The priority flag is not set for this bug.
:spohl, could you have a look please?

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