1598586 - After changing DPI on Windows, focusing/unfocusing Firefox menu items leaves artifacts

Status: NEW

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

Description

[nyanpasu64]

Attachment: firefox 125 to 100 menu.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:70.0) Gecko/20100101 Firefox/70.0

Steps to reproduce:

• Open Firefox when Windows is set to 125% DPI (laptop monitor).
• Switch Windows to 100% DPI (plug in external monitor).
• Open a menu and move my cursor across it.

Actual results:

I get line artifacts after focusing and unfocusing menu items (by moving my mouse down/up the menu, or using arrow keys to navigate it). This occurs on bookmark menus, the main menu, and right-click menus.

On some menus, I get dark lines left behind. On other menus, I get faint blue lines (similar color to focused menu item background).

Moving my cursor outside the menu makes artifacts disappear.

I think this issue is some form of rounding error. Is this related to https://bugzilla.mozilla.org/show_bug.cgi?id=1427524 ?

Expected results:

Moving my mouse over any menu does not leave behind visual artifacts.

Comment 1

[nyanpasu64]

Interestingly, in my above screenshot, dark lines appear every 4 menu items, and the pattern appears almost (but not quite) periodic.

Comment 2

[nyanpasu64]

Attachment: Main menu bar, File menu, light blue artifacts.

Comment 3

[Alice0775 White]

Seems duplication of Bug 1342821 or Bug 1419830

Comment 4

[Timea Cernea [:tbabos][inactive]]

Reproduced the issue on latest Nightly just by changing from default 100% scale resolution to 125%.
Might as well be duped after Bug 1342821, but leaving it as new to raise awareness.

Comment 5

[:Gijs (he/him)]

Based on https://bugzilla.mozilla.org/show_bug.cgi?id=1342821#c8 I think this is a widget issue - it's certainly not a Firefox frontend issue; at best it'd be a XUL layout or gfx issue if it's not just Windows.

Comment 6

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

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

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