1559564 - Per-monitor DPI broken either in latest Firefox or latest Windows

Status: NEW

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

Description

[Katelyn Gadd (:kael)]

Attachment: Screenshot of both monitors side-by-side. Left is 150%, right is 100%

Per-monitor DPI previously worked Somewhat Okay when I moved a window/tab to my other monitor, all the browser chrome scaled based on the DPI and so did the page. Now it doesn't scale at all. I just installed the latest Windows update (may, I think?) but Firefox also installed an update after the reboot, so I don't know which one the problem is.

I checked to see if I had forced DPI compatibility on firefox.exe at some point, but I hadn't. Forcing it into 'Application' mode does not fix this.

Comment 1

[Katelyn Gadd (:kael)]

If I set the scaling mode to 'System' with compatibility settings, it preserves ratios but everything on the 150% monitor is blurry (upscaled from 100). 'System (Enhanced)' is a nightmare and does not work at all.

Comment 2

[Katelyn Gadd (:kael)]

Attachment: image.png

Sigh. Either turning on this compatibility option or turning off 'fix apps that are blurry' in control panel suddenly got me the old behavior. My guess is it was the former, or both in combination, and doing this reset whatever compatibility flags had been set for Firefox.

It works with 'fix blurry apps' turned on now and with that compatibility option turned off, but it was broken before. I'll see if I can repro somehow...

Comment 3

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

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

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