[QGIS-Developer] QGIS and Fedora: My tips

[Tim Sutton]

Hi Nyall

I just upgraded my laptop to fedora 35 last week. Will wait a few more
weeks before doing my desktop too. I will definitely do your
debuginfod tip. The file chooser, yes is irritating but I guess it is one I
will just live with for now since I have some flatpak apps and the fix
seems invasive. The inactive elements colouring hasnt really bothered me
till now so I guess I will keep trucking along.

One other funny thing I found is that the qscintilla library name was
changed to have an underscore rather than a hyphen e.g.

from

/usr/lib64/libqscintilla2-qt5.so

to

/usr/lib64/libqscintilla2_qt5.so

Otherwise the migration was very smooth. Are you running under wayland? I
am still using x11 because none of the video conferencing apps I use work
under wayland. Is there any particular benefit to using Wayland for QGIS
that I am missing out on?


Thanks for this!

Regards

Tim

On Sun, Jan 16, 2022 at 11:33 PM Nyall Dawson <nyall.dawson at gmail.com>
wrote:

> Hi list,
>
> Been hitting some pain points with using/developing QGIS under Fedora
> recently, so I thought I'd summarise the solutions I've found for
> these issues here in case they are of use to anyone else!
>
> (Quite possibly these issues also affect other Linux distros too)
>
> Messed up file open/save dialog window stacking
> -----
> The issue here is that file dialogs (like the open/save file dialogs)
> will frequently open BEHIND the parent window. This one isn't a
> paper-cut, it's a full-on amputated limb and was driving me insane.
>
> The root cause of this is that the gtk implementation of the "file
> chooser" portal specification is buggy, at least for Qt applications.
> I couldn't solve this one, couldn't get upstream to acknowledge, so I
> gave up and found the following hacky solution which completely
> disables the file chooser portal for the system.
>
> Edit /usr/share/xdg-desktop-portal/portals/gtk.portal as root, and
> remove the "org.freedesktop.impl.portal.FileChooser;" string from the
> "Interfaces=" line.
>
> This will force the system to use the standard GTK file chooser
> instead of the sandboxed portal one. It fixes the broken file dialog
> window stacking (yay!) but as a side effect will completely break ALL
> file dialogs used by sandboxed (e.g. flatpak) applications.
>
> For me that's an acceptable compromise (I don't use any flatpak
> applications).. but make your own judgement call here :)
>
> (As an added bonus: the file chooser portal specification is quite
> limited, and doesn't support things like showing a "save as" file
> dialog which **doesn't** warn about overriding existing files. As a
> result things don't work nicely in QGIS, and you'll get UI gremlins
> like the "save vector layer" dialog incorrectly warning that an
> existing GPKG file will be overwritten even though you're only
> appending a new layer to that file, not overwriting it).
>
>
> Debug sessions of QGIS just "hang"
> ----
>
> I noticed this one after upgrading to Fedora 35. Trying to run any
> session of QGIS under a debug environment (eg. gdb) just resulted in a
> hang at startup.
>
> I tracked this one down to this change:
> https://fedoraproject.org/wiki/Changes/DebuginfodByDefault, where
> Fedora 35 enables "debuginfod" by default.
>
> debuginfod is supposed to be a helpful thing which downloads debug
> info on demand. The "hang" during startup of QGIS debug is actually
> just debuginfod trying to download all the debug info for libraries
> used by QGIS. BUT... it's an INSANE amount of data it's trying to
> download. debuginfod is trying to download debug info for every single
> library used by QGIS recursively. Which results in it trying to even
> download debug info for webkit, which is so large that I could never
> get the download to ever complete!!! Even worse, debuginfod defaults
> to auto-deleting all downloaded debug info on a weekly basis.... so if
> you were super-patient and waited for this to download then you'll
> just have to go through the same thing again in a week.
>
> Solution: disable debuginfod, by unsetting the DEBUGINFOD_URLS
> environment variable. Debug sessions of QGIS will start just like they
> always used to.
>
>
> Bad coloring of unfocused UI elements
> ------
> There's an annoying issue under recent gnome/gtk releases where
> unfocused UI elements in Qt applications are incorrectly styled with
> the "inactive window" coloring. This results in widgets like lists,
> tree views, and dock child widgets showing as though they are disabled
> whenever they aren't the currently focused widget. (It's described
> upstream here https://github.com/FedoraQt/adwaita-qt/issues/126)
>
> I couldn't find a proper fix for this one, so I've just submitted a
> gross hack to QGIS to completely disable the inactive window coloring
> on these environments (https://github.com/qgis/QGIS/pull/46847). This
> hack will fix the theming on QGIS 3.24+.
>
>
> Hope those tips are of use to someone!
>
> Nyall
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-- 
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​

Tim Sutton
Visit http://kartoza.com to find out about open source:
 * Desktop GIS programming services
 * Geospatial web development
* GIS Training
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Tim is a member of the QGIS Project Steering Committee
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