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To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject: octave doesn't work any longer with qt graphics toolkit
Thread-Topic: octave doesn't work any longer with qt graphics toolkit
Thread-Index: AdkmkqXCJLCfaHDLSl2jeDELGKdI5w==
Date: Thu, 12 Jan 2023 14:32:08 +0000
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From: Wyser Klaus via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Wyser Klaus <Klaus DOT Wyser AT smhi DOT se>
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Hej---

I got a new computer in September and installed Cygwin/X11 and many more packages, among others Octave (I think it was 5.2 back then). I have been using cygwin and octave for 20 years already, so I'm not new to this. Well, everything worked just fine until I happened to update some cygwin packages in December, among others octave (to version 6.4). Unfortunately I didn't pay attention to what else was updated in that go, usually these regular updates (marked as "pending" in the setup) just work fine. Not this time though: octave is still working, but not the graphics output. When entering a command to plot something a figure window opens under X11, but it is just a copy of the background and doesn't show what I wanted to plot. Octave doesn't freeze, I can still work and do all the math stuff, it's just the plotting that doesn't work any longer. After some troubleshooting I found that it likely is a problem with the graphics_toolkit, I can make plots if I set it to "gnuplot" but get th
 e problem when it is set to "qt" (which is the default).

So should I use "gnuplot" then? Well, that's not really an option because gnuplot doesn't allow interaction with the figure (rotating, zooming), and some of the more complicated plotting routines don't work properly any more (e.g. contour plots). 

First I suspected this being a problem of the Octave update, but apparently it's not the case. Even when going back to Octave 5.2 I still have the same problem with the figure window. Searching the Internet didn't help, so I wonder if I'm the only one having this problem with Octave? As said above, I don't know exactly what other Cygwin packages have been updated at the same time, so in principle it is possible that there is an incompatibility with some other packages (OpenGL?) that were updated at the same time, I tried reverting some libraries but it didn't help. I also tried to isolate the problem by installing a very limited Cygwin setup from scratch, basically only X11 and Octave, nothing else. I get the exact same error even with this very restricted setup.

When searching for help I also came across this page: https://wiki.octave.org/Octave_for_Microsoft_Windows There is a Windows version of Octave that can be installed independently from Cygwin (relying on mingw64 in my case) and that installation works well (including graphics). This is also a newer version of Octave (7.3) compared to the Cygwin package (6.4). The Windows installation is a fallback option, however, I cannot integrate it with my Cygwin environment which makes my workflows way more complicated and I would prefer to have an Octave package for Cygwin.

So my questions are:
- Am I the only one in the Cygwin/X11 community with this kind of Octave problem?
- Is there something I can do about it (OpenGL/Qt...)?
- Will there soon be a new Octave 7 release for Cygwin that hopefully solves all my problems?

Any help is greatly appreciated, thanks.

=====
Klaus Wyser
Rossby Centre
SMHI


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