If something is drawn by wxWidgets and is horizontally scrollable if wxWidgets uses GTK3 it is likely to flicker on redraw.

Upstream bug report: https://trac.wxwidgets.org/ticket/18462. The problem is reproducible by the maintainer of wxWidgets. It doesn't happen in wxWidgets3.1, which (as it is a development version) isn't packaged with debian.

Do either of the suggestions pcor makes on the upstream ticket help?

Cheers,
    Olly

wild has flooded my inbox with one mail every 90 seconds and I therefore
didn't see the answer to my bug report there.

Kind regards,

    Gunter.

[Moving this thread from bug #894663 to #934386]

So, are you going to upload an updated wxmaxima to unstable?

Or would you like me to NMU?  I already have a test build of a fixed
wxmaxima package so I easily can if your limited laptop battery
situation is the obstacle.

Also, is this bug (#934386) specific to X11?  A comment you made
elsewhere seemed to imply it is which is rather important information,
but X11 vs wayland isn't mentioned here at all, and only tangentially in
the upstream ticket.

Cheers,
    Olly

Thanks for the offer of doing an NMU.

Currently the wxMaxima manual is in transition from a HTML file made
with a proprietary tool to a .md file that can be edited by the
maintainers and (using pandoc and po4a) can be converted into localized
HTML.

As soon as that is done a new wxMaxima release will take place that I
will upload to unstable: I was trying to avoid uploading a
nearly-obsolete version of the program.

Kind regards,

  Gunter.

Thanks, done.

That sounds great in the wider context, but any changes to how you
maintain your docs are not even slightly relevant to this transition.

There's no need for a new upstream release to make a Debian upload.
That's a common trap to fall in to when Debian maintainer is upstream
(I know I fell into it myself when I was new to Debian) but it's not a
helpful approach to take - it results in delaying making fixes to
Debian, and pointless release churn upstream.

The question should really be whether an upload would be an improvement
over what's currently in Debian, not whether it's better than some
not-yet-existing upcoming release.  In your mind the version we'd upload
is "nearly-obsolete", but then the version currently in unstable it
would replace is at least as much so.

By uploading the change now we get wider testing of it, especially if
your new upstream release takes longer to make.  This way you don't
need to feel under time pressure to make the upstream release to address
this bug, but if your new release is ready you can just upload and we've
only lost the small amount of time it took for me to rebuild the
package.

Cheers,
    Olly

All the workarounds for crashes due to gtk3 bugs would have been relevant, though => will make a new release as soon as I can.

Kind regards,

   Gunter.

Crashes?  I don't think you've reported any crashes...

I thought the two remaining bugs affecting wxmaxima were the
two finger touchpad scroll not working, and scrolling flickering?

Neither is ideal but neither is a crash.

Oh, and perhaps a wxDC::Clear() issue which upstream closed but
you claimed still isn't working.  Though I noticed in your current
git master `WORKING_DC_CLEAR` always ends up defined (by line 370 of
src/Worksheet.cpp) and so your rectangle drawing workaround is never
actually used.  I didn't see any obvious window clearing issues in my
testing FWIW.  But anyway, this one wasn't a crash either.

Cheers,
    Olly

I fix about five bugs in wxMaxima a week. Reporting a bug to debian
costs at least one week of work and wxMaxima is using enough of
wxWidget's functionality that it has the potential of being a near-ideal
bug detector for wxWidgets  => If I can work around a bug I do that
instead of reporting it. Else we would need a bigger team for supporting
wxMaxima.

As there have been no new bug reports after the wxMaxima version from
July was uploaded I am rather curious if any of the problems I've
encountered are likely to materialize on other computers. Perhaps I have
managed to transform my system into a quite complete test case somehow -
which isn't bad as until now I've been able to reproduce (and in most
cases to resolve) all bug reports I got for wxMaxima.

Kind regards,

    Gunter.

Control: tags -1 +unreproducible

The upstream ticket has been in state "infoneeded_new" for more than 3
weeks requesting you explain how to reproduce this in the "scroll"
sample - so far without response.  Tagging this "unreproducible" which
roughly matches the upstream status, and because neither Scott nor
myself seem to be able to reproduce this based on the information you've
so far provided.

Cheers,
    Olly

|Wild Update:
|

|After an|

|   export GTK_IM_MODULE=xim|

|the combination GTK3.0, wxWidgets and any ribbon, nearly any list view
and all scrolled windows flicker real bad. At least if the CPU power
doesn't allow for a repaint before the data arrives at the screen.
Examples of flickering things are wxWidget's scroll and the ribbon sample.
|

|After an|

||   export GTK_IM_MODULE=ibus||

||the flicker is completely gone.
||

||Can anybody think of any reason why this even remotely follows any logic?
||

||
||

||Kind regards,||

||    Gunter.
||

It seems xim support in GTK3 is known to be buggy and GTK upstream say:

    the recommended fix is not to use xim

https://gitlab.gnome.org/GNOME/gtk/-/issues/2560#note_757143

Support for xim has been removed completely in the development branch
which is leading to GTK4:

    support for the xim input method has been removed in favor of IBus

https://blog.gtk.org/2020/02/13/gtk-3-98/

Cheers,
    Olly

As above, this is really a bug in Gtk not wxWidgets.  Gtk upstream have
explicitly said the fix it to avoid xim, so it seems pointless to
reassign it, and I'm just going to close this bug.

The upstream wxWidgets FAQ now mentions this issue, and also recommends
avoiding xim as the solution:

https://wxwidgets.org/docs/faq/gtk/#xim

Also upstream have released wxWidgets 3.2.0 and Scott's working on
packaging it.  That shows a warning message on stderr if XIM input
method is in use:

https://github.com/wxWidgets/wxWidgets/pull/2138

Cheers,
    Olly