1588330 - hamburger menu does not display correctly on multiple monitor configuration

Status: REOPENED

(Firefox :: Menus, defect, P3)

Description

[ceyring12]

Attachment: display1.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0

Steps to reproduce:

My configuration:

• Dark mode theme
• Windows 10
• two monitors in extended display mode

1. Laptop/Surface display, 150% scale, 2160 x 1440 resolution
2. External display, 125% scale, 3440 x 1440 resolution

Actual results:

The hamburger menu does not 'grow' long enough to fit the elements within it on the primary display. It works fine on the second display.

Expected results:

The hamburger menu should appropriately display all elements that are able to fit on the screen. This is a issue - it may have started with a Windows update, a Firefox update, or a change in my system settings. It had always worked fine before.

Comment 1

[ceyring12]

I'll also mention that the displays are configured to be stacked one on top of each other. Firefox may be using the combined height of all displays to calculate the height of the expanded menu.

Comment 2

[Jared Wein [:jaws] (please needinfo? me)]

Are there any errors in the Browser Console (Ctrl+Shift+J) when this happens?

Does this stop happening if you disconnect the external display? Does this stop happening if you change your DPI scale to 100% or 200%?

Comment 3

[ceyring12]

Ok so this is strange behavior, but I've figured out how to repeat it. The problem seems to be associated with both the dual display configuration and the scaling.

If I disconnect my external monitor, this fixes the issue. If I reconnect the monitor, the issue reappears on my laptop display. The external display works fine in either case.
With both displays connected, if I adjust the scaling on the laptop display to 100% or 125%, the problem disappears.
If I change the external display from 125% to 150% while the laptop display is set to 150%, the problem disappears. If I readjust the external display back down to 125%, the problem reappears.

This also appears to be related to the fact that my external display is set as my 'main display' in Windows. If I change the main display to be my surface laptop, I cannot get this bug to repeat regardless of what scaling solutions I select. I think Firefox might be drawing the menu based on the scaling number of the 'main display', rather than the display the window is located on. It works fine when the scaling is set to be the same or less than the external display.

The browser console had some errors in it, but I am not sure if they are related. I've uploaded a screenshot.

Comment 4

[ceyring12]

I can't figure out how to upload a screenshot... but it is here: https://imgur.com/KlVIWOr

Comment 5

[giuseppe.passino]

This might impact me as well https://bugzilla.mozilla.org/show_bug.cgi?id=1658770

Comment 7

[Raluca Popovici, Desktop QA]

I wasn't able to reproduce this issue on Fx 86.0a1(2021-01-22) , win 10x64 with 2x external displays: a 4K (3840x2160) - scale 125% and a 1920x1080 - scale 150%.

Comment 8

[ceyring12]

This issue has not been fixed. I was just able to repeat it. Using FF 85.0 64-bit.