bugGNU Octave - Bugs: bug #57707, Octave GUI fails to start if it...


bug #57707: Octave GUI fails to start if it was last open on monitor 2 of a 2 monitor system

Submitted by:  James Watts <jpwatts>
Submitted on:  Fri 31 Jan 2020 12:36:00 PM UTC  
Category:  GUI Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Unexpected Error
Status:  None Assigned to:  None
Originator Name:  James Watts Open/Closed:  Open
Release:  5.1.0 Operating System:  Microsoft Windows

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Mon 17 Feb 2020 10:25:15 AM UTC, comment #5: 

PS, sorry the mouse is so noisy on the video - I think it needs a backing track!

James Watts <jpwatts>
Mon 17 Feb 2020 10:23:03 AM UTC, comment #4: 

@Torsten: I have reproduced the issue on my laptop with a slave monitor (slightly different configuration to the original problem I had). 

I have uploaded a video of the process on OneDrive at:

The steps I take are:

(Starting with slave monitor set as only display)

1. Open Octave.  Everything works.  Close it again.
2. Set Dual display mode: Multiple displays 'Extend these displays'
3. Open Octave.  Everything works - Octave opens on the laptop (Primary) display.
4. Move Octave to the Slave display then close it.
5. Set Single display mode: Multiple displays 'Show only on 2'
6. Open Octave.  Doesn't work.  Icon appears on taskbar, with blank window showing when I hover over it.
7. Force close Octave.
8. Set Dual display mode: Multiple displays 'Extend these displays'
9. Open Octave.  Everything works - Octave opens on the Monitor (slave) display.
10. Move Octave window to the Laptop (Master) display then close it.
11. Set Single display mode: Multiple displays 'Show only on 2'.
12. Open Octave.  Everything works again.  Phew!

The video file is about 240MB, and I apologise that I had to shoot it on a smartphone because I couldn't find a way of recording both displays as they changed configuration.

I've uploaded details of the PC configuration and Octave help page.

Thank you so much for your help.

And also, thank you all for the time you give up to maintain this amazing software.  I guess the bugs report is just a list of things that go wrong, but thank you so much for everything that goes right!

All the best,


James Watts <jpwatts>
Sun 16 Feb 2020 12:08:53 PM UTC, comment #3: 

@James: I have tested the issue described in the OP but could not reproduce the issue: Restarting octave without a second monitor just opened the application on the main screen. However, this test was with a recent build from the default branch and with windows in a virtual box having two screens.

I recognized that on my (non-virtual) Debian/Gnome setup, unplugging a second monitor is not immediately recognized by the system (the 2nd monitor was still shown in the in the system configuration, which would lead to the same effect you have described in your post). Could you please check if the display configuration in window is only showing the master screen when you run into the issue?

Torsten Lilge <ttl>
Project Member
Fri 31 Jan 2020 08:31:11 PM UTC, comment #2: 

Philip, I guess the report you are referring to is bug #53207. After a quick look at the comment of the related changeset, the issue reported here should also have been fixed. But I will take a closer look over the weekend.

Torsten Lilge <ttl>
Project Member
Fri 31 Jan 2020 03:13:03 PM UTC, comment #1: 

IIRC there's a similar bug report (fixed) [*] about GUI window panes on a 2nd monitor (main window on monitor #1) that got inaccessible once that 2nd monitor was unavailable; similar to your case but in my case it was with remote desktops, logging in from a 1-monitor setup to my 2-monitor work box in another branch office.
Maybe that bug report should be reopened, or is this one sufficiently different to warrant a new bug report?

([*] Sorry I can't find the bug report; I'm quite sure I entered it  myself but searching in My Items doesn't turn it up, whatever option I use)

Philip Nienhuis <philipnienhuis>
Project Member
Fri 31 Jan 2020 12:36:00 PM UTC, original submission:  

I have a laptop running Windows 10 with Octave 5.1.0.  When it is docked, the laptop has 2 monitors.

I ran the Octave GUI, displayed on Monitor 2 (the slave monitor) which is an extended desktop from the Master monitor. 

When I tried to run Octave undocked, on the laptop screen, it wouldn't start.  It created an icon on the taskbar then did nothing else.  When I hovered over the icon with the mouse, it displayed an empty preview window.

I tried lots of things to resolve it: power cycle, reinstall, install 32bit version, reinstall 64bit version and the same behaviour persisted.  The CLI version ran fine throughout this.

I fixed it by opening Octave when docked, moving the window into the main monitor, then closing again.  Now it opens fine on the laptop screen when not docked.

I suspect that Octave stores its last screen position, but if the last screen position was on a monitor that isn't there any more it just hangs and waits for it.  (Rather than initialising to a default location).

James Watts <jpwatts>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

Attached Files
file #48432:  about@octave.png added by jpwatts (16KiB - image/png - PC details)
file #48433:  pc@details.png added by jpwatts (73KiB - image/png - PC details)


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    Date Changed by Updated Field Previous Value => Replaced by
    2020-02-17 jpwatts Attached File- => Added about@octave.png, #48432
        Attached File- => Added pc@details.png, #48433

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