1426874 - scaling issues on 4k monitors when games change resolution

Status: NEW

(Core :: Widget: Win32, defect, P3)

Description

[sammax]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20171206182557

Steps to reproduce:

1. Have a Windows 10 computer with a 4k monitor, set scaling to more than 100%
2. Open Firefox
3. Open a full-screen Game that uses a lower resolution, e.g. 1080p
4. Alt-Tab to Firefox


Actual results:

When the resolution is changed back to 4k, scaling of the whole desktop is initially 100%, then it changes to whatever the user selected scaling value is.
Scaling of the Firefox window stays at 100% however.
Restarting Firefox or manually changing the scaling value sets the correct scaling for Firefox again.


Expected results:

Firefox should re-scale when the rest of the Desktop does.

Comment 1

[Alex]

I hit this today, I'm pretty sure it's a Windows bug since I've seen similar behavior in other apps (Like Explorer rendering UI elements half sized and text normal sized, etc.)

It doesn't happen every time for me, I'm not sure if Windows is sending the events out of order or something (e.g. DPI change then resolution change instead of resolution change and then DPI change), so even if Firefox re-queries the system for the DPI if it detects a resolution change then it might not pickup on the right value.

Comment 3

[pravin]

Attachment: Untitled.png

I want to report a similar issue. For me, the steps to reproduce are different and inconsistent.

Environment - I have a two monitor setup - a 4k monitor at 3840 x 2160 pixels and a regular 1080p monitor (1920 x 1080 pixels). I usually have my 1080p monitor switched off. I'm running Windows 10, build 21390. FF is v89.0.2.

This bug occurs inconsistently in these two scenarios,

1. When I am using both monitors at the same time.
2. When I am using the 4k monitor with FF on it. Then I switch to my 1080p monitor and turn off the 4k monitor.

Steps to reproduce (Scenario 1)

1. Dragging the FF window from the 4k monitor to the 1080p monitor results in a scaled up UI (including tabs and min/max/close buttons).

Steps to reproduce (Scenario 2)

1. I am using the 4k monitor only. The 1080p is powered off.
2. Use FF normally on the 4k monitor. It assumes the correct scaling(?) and looks good.
3. Turn off power to the 4k monitor. Turn on power to the 1080p monitor.
4. Switch to FF. Sometimes, the FF windows don't re-scale. Everything else in the Windows environment scales properly.

I've attached a screenshot with the same website on Edge and FF browsers next to each other.