Hi,

I'm not saying that it isn't related to _NET_WM_FRAME_DRAWN, but I don't
think it should be for the following reasons:

   - I would expect it to affect only software rendering, since with ES2
   the rendering is handled by OpenGL and does not rely on GDK/GTK for
   rendering.
   - Disabling frame synchronization with
   gdk_x11_window_set_frame_sync_enabled() does not change the behavior.
   - Popups are override-redirect windows, so theoretically the window
   manager/compositor should not manage or otherwise interfere with them.

-- Thiago

Em ter., 18 de ago. de 2026 às 13:57, Martin Fox <[email protected]>
escreveu:

> I was able to reproduce this bug while using xtrace and confirmed that the
> _NET_WM_FRAME_DRAWN message is not being sent. BTW it takes a lot longer to
> reproduce this with xtrace.
>
> I’ve written a standalone GTK 3.0 application that demonstrates the
> problem. I’ll attach it to the JBS ticket.
>
> So far I’ve only been able to reproduce this on Ubuntu 24 LTS with Xorg as
> the backend. When I run Ubuntu 24 under Wayland I can’t get it to
> reproduce. In Ubuntu 26 Wayland is the only option so I can’t reproduce the
> bug there, either.
>
> The frame lock freezing and thawing is internal to GDK and looking at the
> sources I don’t see any way to thaw it externally.
>
> Martin
>
> > On Aug 16, 2026, at 3:19 PM, Thiago Milczarek Sayão <
> [email protected]> wrote:
> >
> > The issue cannot be reproduced when running with GDK_SYNCHRONIZE=1 (not
> > recommended; used for testing purposes only).
> >
> > I've tried a few workarounds, but so far, none of them have been
> successful.
> >
> >
> >
> > Em dom., 16 de ago. de 2026 às 02:41, Christopher Schnick <
> > [email protected]> escreveu:
> >
> >> Would there be any way to guard against the bug from the JavaFX-side so
> >> that an invisible popup won't be shown when it happens? Doesn't have to
> >> be pretty, just to avoid the most glaring issue
> >>
> >> On 16/08/2026 02:56, Thiago Milczarek Sayão wrote:
> >>> Hi,
> >>>
> >>> It seems that this is a bug in Mutter.
> >>>
> >>> I tried disabling frame synchronization using
> >>> gdk_x11_window_set_frame_sync_enabled(), but the issue still occurs.
> >>>
> >>> I also tried forcing an Expose event after the popup was mapped, but
> that
> >>> did not solve the problem either.
> >>>
> >>> The popup window is mapped correctly, but occasionally it is not
> rendered
> >>> on screen.
> >>>
> >>>
> >>> See (the video shows one run, but i did many with the same result):
> >>>
> >>> youtube.com/watch?v=1LB2OLrYex8&feature=youtu.be
> >>>
> >>> Xephyr :100
> >>>
> >>> DISPLAY=:100 java @/home/tsayao/jfx/build/run.args  AutoPopupTest.java
> >>>
> >>> Test 1:
> >>> No window manager - bug does not happen
> >>>
> >>> Test 2:
> >>> kwin - bug does not happen
> >>> DISPLAY=:100 dbus-run-session kwin_x11 --replace
> >>>
> >>> Test 3:
> >>> mutter - bug happens
> >>> DISPLAY=:100 dbus-run-session -- mutter --x11
> >>>
> >>> -- Thiago.
> >>>
> >>>
> >>>
> >>> Em ter., 11 de ago. de 2026 às 20:18, Martin Fox <
> [email protected]
> >>>
> >>> escreveu:
> >>>
> >>>> For those of you who haven’t looked at the bug report, it has to do
> with
> >>>> GDK expecting the windowing system to send it a _NET_WM_FRAME_DRAWN
> >> message
> >>>> but the message never arrives. If this is something you have any
> >> experience
> >>>> with feel free to jump in and investigate (because I’m at a loss).
> >>>>
> >>>> It looks like we’re not the only one seeing this. I ran across a
> thread
> >>>> detailing how GVim sometimes freezes (vim/vim repository on GitHub,
> >> issue
> >>>> #12671) and they also concluded it was due to GDK not receiving this
> >>>> message. The Discourse discussion contains more information (link in
> the
> >>>> JBS ticket). They were not able to resolve the problem.
> >>>>
> >>>> Martin
> >>>>
> >>>>> On Aug 10, 2026, at 11:59 AM, Andy Goryachev <
> >> [email protected]>
> >>>> wrote:
> >>>>> I think this scenario warrants bumping the issue to P3.
> >>>>>
> >>>>> -andy
> >>>>>
> >>>>>
> >>>>> From: PavelTurk <[email protected]>
> >>>>> Date: Sunday, August 9, 2026 at 23:55
> >>>>> To: [email protected] <[email protected]>
> >>>>> Subject: [External] : Using JavaFX on Linux can be dangerous
> >>>>>
> >>>>> Hi everyone,
> >>>>>
> >>>>> I would like to warn everyone and provide some feedback regarding the
> >>>>> use of JavaFX on Linux. We developed a small application and gave it
> to
> >>>>> a small number of the customer’s employees for testing. The
> application
> >>>>> was tested on both Linux and Windows.
> >>>>>
> >>>>> We encountered serious problems on Linux. Due to bug JDK-8371781,
> popup
> >>>>> windows are not displayed to the user, but they are still present in
> >> the
> >>>>> scene. As a result, a user can click on elements in these popups
> >> without
> >>>>> being able to see them, potentially triggering actions that they
> >>>>> absolutely should not be able to perform.
> >>>>>
> >>>>> Therefore, I decided to bring this issue to the attention of the
> JavaFX
> >>>>> developers and warn others about the potential safety implications of
> >>>>> using JavaFX on Linux.
> >>>>>
> >>>>> Best regards, Pavel
> >>>>
> >>
>
>

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