1291420 - Firefox stops responding when secondary monitor becomes primary

Status: RESOLVED INCOMPLETE

(Core :: General, defect)

Description

[WBT]

I have noticed this bug for a long time but have not quite been able to get it down into a bug report; maybe comments here will help.

When I have Firefox open on a Windows 7 Pro laptop that is connected to a second monitor/projector in Extend Desktop mode, it generally works fine.  However, if I change the monitor/projector setting to be Projector Only, and all windows move over to the second monitor (as expected), Firefox stops responding.  Any audio playing (e.g. Pandora) gets paused.  Firefox continues in this "Not Responding" state indefinitely, until the projection mode is changed back to Extend, at which time it immediately resumes normal functionality and audio playback resumes (though for Pandora, after playing out the buffer it suddenly stops that song and moves to the next). 

Observed behavior: Firefox is nonfunctional in Projector Only mode.
Expected behavior: Even in Projector Only mode, Firefox is responsive and functions normally, as a window on that second screen, like all other windows.

I was able to reproduce this with all add-ons manually disabled, by going down the add-ons list and clicking Disable next to each, then restarting twice.  Oddly, the restart obtained by clicking Restart now after disabling some add-on led to a functional instance where the bug was not observed, but manually restarting again without changing any add-on states led to a buggy instance.  Also, though the bug is observed with all add-ons disabled, choosing "Restart with Add-ons Disabled" from the Help menu produces a functional instance where the bug is not observed.  

Does anybody have any ideas about what might be causing this, or what else could help narrow it down?

Comment 1

[:Gijs (he/him)]

(In reply to WBT from comment #0)
> I have noticed this bug for a long time but have not quite been able to get
> it down into a bug report; maybe comments here will help.
> 
> When I have Firefox open on a Windows 7 Pro laptop that is connected to a
> second monitor/projector in Extend Desktop mode, it generally works fine. 
> However, if I change the monitor/projector setting to be Projector Only

In what kind of application or with what keys / controls do you change this setting?

When you say Firefox stops responding, is it just audio that stops playing, or does the user interface stop responding to clicks etc.?

Did this ever use to work correctly?

Comment 2

[Emil Pasca [:emilpasca]]

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:51.0) Gecko/20100101

I have tested this issue on Windows 7 x64 with the latest Firefox release (48.0.2) and the latest Nightly (51.0a1-20160830030201) and could not reproduce it.
When switching from Extended mode to Projector Only mode, Firefox is responsive and functions normally, all windows are moved to that view and are functional.

Can you please retest this using the latest Firefox release and  the latest Nightly build (https://nightly.mozilla.org/) and report back the results? When doing this, please use a new clean Firefox profile, maybe even safe mode, to eliminate custom settings as a possible cause (https://goo.gl/PNe90E).

Comment 3

[Emil Pasca [:emilpasca]]

Marking this as Resolved - Incomplete due to the lack of response from the reporter.

If anyone can still reproduce it on latest versions, feel free to reopen the issue and provide more information.

Comment 4

[Firefox Bug Husbandry Bot]

Moving from Core::Untriaged to Core::General https://bugzilla.mozilla.org/show_bug.cgi?id=1407598